Daylighting sheet, daylighting panel and roll-up daylighting screen

ABSTRACT

An object is to provide a daylighting sheet which efficiently performs daylighting and in which, when the daylighting sheet is applied to a window of a building or the like, it is possible to see an outdoor side. 
     The daylighting sheet includes a translucent base material layer; and a light deflection layer that is formed on the base material layer, and the light deflection layer includes: light transmission portions that are aligned along one surface of the base material layer so as to be able to transmit light, each of the light transmission portions including a portion that is convex upwards; and light deflection portions that are formed between the light transmission portions and filled with a material whose refractive index is lower than that of the light transmission portions.

TECHNICAL FIELD

The present invention relates to a daylighting sheet, a daylightingpanel and a roll-up daylighting screen that are units for taking outsidelight such as sunlight into the interior of a building or the like.

BACKGROUND ART

It is well known that outside light such as sunlight is taken into theinterior of a building through a so-called window glass or the like suchthat a comfortable indoor space is formed. By contrast, severaltechnologies have so far been proposed in which direct sunlight iscontrolled such that outside light is taken in a more comfortable form.

For example, patent document 1 discloses a light control sheet that isarranged in a light taking-in portion which takes sunlight into abuilding and that is used for controlling the taking in of sunlight. Inthe light control sheet, the entire sheet is formed with a lighttransmission portion made of a light transmission material whichtransmits sunlight and a light shield portion group made of a lightabsorption material which absorbs sunlight, and in the light shieldportion group, in one direction within the sheet, with a predeterminedpitch, a plurality of a light shield portions made of the lightabsorption material are aligned.

According to technologies disclosed in patent documents 2 to 4, aninterface that has a predetermined geometric configuration such as aprism and has a refractive index difference is utilized, and thuscontrol is performed by deflecting and reflecting outside light such assunlight in a desired direction.

RELATED ART DOCUMENT Patent Document

Patent document 1: Japanese Unexamined Patent Application PublicationNo. 2010-259406

Patent document 2: International Publication No. WO93/25792

Patent document 3: Japanese Unexamined Patent Application PublicationNo. 2003-157707

Patent document 4: Japanese Unexamined Patent Application PublicationNo. 2000-15712

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention

However, in the light control sheet configured as disclosed in patentdocument 1, since most of outside light (sunlight) is absorbed by thelight shield portion group, when the light control sheet is applied tothe window of a building or the like, it is difficult to efficientlytake outside light into a room.

Although in the technologies disclosed in patent documents 2 to 4, it ispossible to control light that enters from the outside, since an imageis refracted by deflection or the like even when the outside is seenfrom an indoor side, sharpness for viewing outside scenery isinsufficient.

In view of the foregoing problem, the present invention has an object toprovide a daylighting sheet which allows efficient daylighting and withwhich it is possible to see an outdoor side from an indoor side when thedaylighting sheet is applied to a building opening portion such as awindow. A daylighting panel and a roll-up daylighting screen that usesuch a daylighting sheet is provided.

Means for Solving the Problem

The present invention will be described below.

One aspect of the present invention is a daylighting sheet that isarranged in an opening portion of a building and transmits light from anoutdoor side to an indoor side, wherein the daylighting sheet is formedby stacking a plurality of layers, the layers include: a translucentbase material layer; and a light deflection layer that is formed on thebase material layer, and the light deflection layer includes: lighttransmission portions that are aligned along one surface of the basematerial layer so as to be able to transmit light, each of the lighttransmission portions including a portion that is convex upward, theportion being in a top side in a position where the light transmissionportion is arranged in the opening portion of a building; and lightdeflection portions that are formed between the light transmissionportions and filled with a material whose refractive index is lower thanthat of the light transmission portions.

In the above daylighting sheet, the light transmission portion mayfurther include a portion that is concave downwards in a light enteringside of the portion that is convex upwards.

In the above daylighting sheet, the light deflection portions may befilled with air.

In the above daylighting sheet, the light deflection portions may befilled with a transparent resin.

A portion in a bottom side of the light transmission portion, theportion being opposite to the portion that is in a top side, may be astraight line on a cross section

In the above daylighting sheet, at least one of other translucent layersmay be arranged on a side of the light deflection layer opposite to thebase material layer.

The light transmission portions may have a predetermined cross sectionand extend along the one surface of the base material layer, and may bealigned in a direction different from the direction in which the lighttransmission portions extend, and the light deflection portions may bearranged between the adjacent light transmission portions such that thelight deflection portions extend in the same direction as the lighttransmission portions and may be aligned in the direction different fromthe direction in which the light transmission portions extend.

Also provided can be a daylighting panel comprising: a translucentplate-shaped panel; and the above daylighting sheet that is attached toone surface of the panel.

Also provided can be the panel that is a window glass that is providedin the opening portion of the building.

Also provided can be a roll-up daylighting screen comprising: the abovedaylighting sheet; and a shaft member that is arranged in thedaylighting sheet such that the daylighting sheet can be wound andunwound.

Effects of the Invention

With the daylighting sheet, the daylighting panel and the roll-updaylighting screen of the present invention, it is possible to allowefficient daylighting and see an outdoor side from an indoor side whenthey are applied to an opening portion such as the window of a building.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 A perspective view of a building 1 where windows 2 havingdaylighting panels 10 are arranged;

FIG. 2 A front view of the window 2 to which the daylighting panel 10 isapplied;

FIG. 3 A diagram showing a cross section of the daylighting panel 10 andschematically showing the configuration of its layers;

FIG. 4 A diagram illustrating the reflection of light in a lightdeflection portion 19;

FIG. 5 A diagram showing a cross section of a daylighting panel 30 andschematically showing the configuration of its layers;

FIG. 6 A diagram showing a cross section of a daylighting panel 40 andschematically showing the configuration of its layers;

FIG. 7 A diagram of an enlarged part of a light deflection layer 17 ofthe daylighting panel 40;

FIG. 8 A diagram illustrating an optical path example in the lightdeflection layer 17;

FIG. 9 A diagram illustrating a case where the culmination altitude ishigh;

FIG. 10 A diagram illustrating a case where the culmination altitude islow;

FIG. 11 A diagram showing a cross section of a daylighting panel 50 andschematically showing the configuration of its layers;

FIG. 12 A diagram of an enlarged part of a light deflection layer 57;

FIG. 13(a) is a diagram illustrating a light deflection portion 59′,FIG. 13(b) is a diagram illustrating a light deflection portion 59″;

FIG. 14 A diagram illustrating an optical path example in a lightdeflection layer 57;

FIG. 15 A diagram illustrating another optical path example in the lightdeflection layer 57;

FIG. 16 A diagram of an enlarged part of a light deflection layer 67;

FIG. 17 A diagram of an enlarged part of a light deflection layer 77;

FIG. 18 A diagram of an enlarged part of a light deflection layer 87;

FIG. 19 A perspective view of a roll-up daylighting screen 90;

FIG. 20 A diagram showing a cross section of a daylighting sheet 15 ofthe roll-up daylighting screen 90 and schematically showing theconfiguration of its layers;

FIG. 21 A diagram showing a cross section of a daylighting panel 100 andschematically showing the configuration of its layers;

FIG. 22 A diagram obtained by enlarging part of the daylighting panel100 and illustrating it;

FIG. 23 A diagram obtained by enlarging part of a daylighting panel 110and illustrating it;

FIG. 24 A diagram illustrating a light deflection layer 157 of adaylighting panel 150;

FIG. 25 A diagram illustrating a shape of a light deflection portion158;

FIG. 26 A diagram showing a cross section of a daylighting panel 120 andschematically showing the configuration of its layers;

FIG. 27 A diagram obtained by enlarging part of the daylighting panel120 and illustrating it;

FIG. 28 A diagram obtained by enlarging part of a daylighting panel 130and illustrating it; and

FIG. 29 A perspective view of a roll-up daylighting screen 140.

BEST MODE FOR CARRYING OUT THE INVENTION

The effects and advantages of the present invention described above willbecome obvious from the following description of the embodiments of theinvention. The present invention will be described below based on theembodiments shown in drawings. However, the present invention is notlimited to the embodiments.

FIG. 1 is a diagram illustrating a first embodiment, and is aperspective view of the appearance of a building 1 including windows 2(see FIG. 2). The building 1 is a so-called office building, and in theouter wall on the south side, a plurality of opening portionscommunicating indoors and outdoors are provided, and here, the windows 2including daylighting panels 10 are arranged.

In FIG. 2, the daylighting panel 10 is formed with a daylighting sheet15 (see FIG. 3), and FIG. 2 is a diagram when the window 2 to which thedaylighting panel 10 is applied is seen from the front. The window 2 isconfigured to include the daylighting panel 10 and at least a frame 3that is arranged around the perimeter portion of a panel 11 (see FIG. 3)so as to frame the panel 11. The windows 2 are arranged in the openingportions of the building 1. The configuration itself in which, asdescribed above, the window is formed by providing the frame and thepanel within the frame is the same as a known configuration. Hence, aknown shape can be applied to the shape of the frame 3.

Here, the window 2 can also be formed by adhering the daylighting sheet15 to a window previously arranged in a building. In this case, sincethe building includes a normal panel and a frame that frames theperimeter portion thereof, the window 2 can be provided by adhering thedaylighting sheet 15 to the panel.

FIG. 3 is a cross-sectional view of a portion of the daylighting panel10 among a cross-sectional view taken along line III-III of FIG. 2 in avertical direction, and is a diagram schematically showing theconfiguration of its layers. In FIG. 3, for ease of illustration, somesymbols will not be repeated (the same is true for drawings shownbelow).

The daylighting panel 10 includes the panel 11 and the daylighting sheet15 that is adhered to the panel 11 with an adhesive layer 12. Thedaylighting sheet 15 includes a base material layer 16, a lightdeflection layer 17, an adhesive layer 20, a protective layer 21 and ahard coat layer 22. These constituent elements that constitute thedaylighting panel 10 will be described below. FIG. 3 is shown in aposition where the daylighting panel 10 is attached perpendicularly tothe building or the like, and the left of the plane of FIG. 3 is theoutdoor side, the right of the plane is the indoor side, the upperportion of the plane is the top and the lower portion of the plane isthe bottom.

The panel 11 is a plate-shaped translucent panel, such as a window glassor a resin panel, that has translucency and is used for the window of anormal building or a normal vehicle. Hence, as a member of the panel 11,a known plate glass or a resin panel can be used.

Here, as the panel 11, a window glass that is previously arranged in abuilding as described above may be used. In other words, the daylightingpanel 10 can be formed by adhering the daylighting sheet 15 to thewindow included in the building.

The adhesive layer 12 is a layer for adhering the daylighting sheet 15to the panel 11. The material for the adhesive layer 12 is notparticularly limited as long as the adhesion described above can beachieved, and, as the material for the adhesive layer 12, an adherenceagent, an adhesive agent, a photo-curable resin, a thermosetting resinor the like that are known can be used. As an example of the adherenceagent, there is an acrylic adherence agent, and furthermore, there is anadherence agent obtained by combining an acrylic copolymer and anisocyanate compound. However, in terms of the property of thedaylighting panel 10, the material of the adhesive layer 12 preferablyhas excellent translucency and weather resistance.

The thickness of the adhesive layer 12 is not particularly limited butis preferably equal to or more than 10 μm but equal to or less than 100μm. When the adhesive layer 12 is excessively thin, the intimate contactbetween the panel 11 and the daylighting sheet 15 is likely to bedegraded. When the adhesive layer 12 is excessively thick, it isdifficult to make the thickness of the adhesive layer 12 uniform.

The adhesive layer 12 may have the function of absorbing at least one ofan infrared ray, an ultraviolet ray and visible light. The “absorbing atleast one of an infrared ray, an ultraviolet ray and visible light”means that an electromagnetic wave of a predetermined wavelength amongelectromagnetic waves classified into any of an infrared ray, anultraviolet ray and visible light is absorbed. The “absorbing” meansthat 10% or more of the electromagnetic wave of the predeterminedwavelength is absorbed.

In order for the layer to have the function described above, the layerpreferably contains an absorption agent that can absorb at least one ofan infrared ray, an ultraviolet ray and visible light.

Examples of the absorption agent that absorbs an infrared ray includemetal oxide ultrafine particles such as an antimony-doped tin oxide(ATO), a tin-doped indium oxide (ITO) and a phthalocyanine compound. Bythe addition of or the application of these absorption agents to thesurface, it is possible to absorb an infrared ray. As described above,the function of absorbing an infrared ray is added to the daylightingsheet, and thus, for example, the effect of reducing the increase in anindoor temperature in summer to decrease the use of air conditioning isprovided.

Examples of the absorption agent that absorbs an ultraviolet rayinclude: benzotriazole ultraviolet absorption agents (TINUVIN P, TINUVINP FL, TINUVIN 234, TINUVIN 326, TINUVIN 326 FL, TINUVIN 328, TINUVIN 329and TINUVIN 329 FL all of which are made by BASF Japan Ltd.); a triazineultraviolet absorption agent (TINUVIN 1577 ED made by BASF Japan Ltd.);benzophenone ultraviolet absorption agents (CHIMASSORB 81 and CHIMASSORB81 FL all of which are made by BASF Japan Ltd.); and a benzoateultraviolet absorption agent (TINUVIN 120 made by BASF Japan Ltd.). Bythe addition of or the application of these absorption agents to thesurface, it is possible to absorb an ultraviolet ray. The function ofabsorbing an ultraviolet ray is added to the daylighting sheet, andthus, for example, the effect of reducing the adverse effect on the skinof a person within a room and the effect of reducing the colordegradation of furniture within a room are provided.

As the absorption agent that absorbs visible light, light absorptioncolored particles such as carbon black are preferably used. However, theabsorption agent is not limited to them, for example, colored particlesthat selectively absorb a predetermined wavelength according to thecharacteristics of light that needs to be absorbed may be used. Specificexamples of the colored particles include: metal salts such as carbonblack, graphite and black iron oxide; organic fine particles that arecolored by dyes, pigments or the like; and colored glass beads. Amongthem, in terms of cost, quality, availability and the like, the coloredorganic fine particles are preferably used. More specifically, acryliccross-linked fine particles containing carbon black, urethanecross-linked fine particles containing carbon black and the like arepreferably used. By the addition of or the application of theseabsorption agents to the surface, it is possible to absorb visiblelight. The function of absorbing visible light is added to thedaylighting sheet, and thus, for example, it is possible to decreaseglare within a room.

The absorption agents described above are contained, and thus it ispossible to provide, when the daylighting sheet is arranged in thedaylighting portion of a building, a more comfortable indoorenvironment. The absorption agent preferably absorbs an electromagneticwave of a predetermined wavelength among electromagnetic wavesclassified into any of an infrared ray, an ultraviolet ray and visiblelight. The absorption agent may be configured to absorb only an infraredray, may be configured to absorb only an ultraviolet ray, may beconfigured to absorb only visible light or may be configured to be ableto absorb two or more types of an infrared ray, an ultraviolet ray andvisible light. Which wavelength's electromagnetic wave can be absorbedcan be selected as necessary according to the place where thedaylighting sheet is arranged and the purpose of the arrangement. Thewavelength and the rate of absorption of an electromagnetic wave that isabsorbed can be adjusted by adjusting, as necessary, the type and amountof the absorption agent described above.

The rate of absorption of the electromagnetic wave of the predeterminedwavelength described above in the layer containing the absorption agentis preferably equal to or more than 10% but equal to or less than 90%.When the rate of absorption is less than 10%, it is difficult to obtainthe effect of containing the absorption agent whereas when the rate ofabsorption is set at 90% or less, it is easy to adjust a compositionconstituting the absorption agent.

The base material layer 16 is a layer that is a base material forforming the light deflection layer 17, has translucency and supports thelight deflection layer 17 to prevent it from deforming. In terms of whathas been described above, specific examples of the material of the basematerial layer 16 include a transparent resin that has, as mainingredients, one or more of acrylic, styrene, polycarbonate,polyethylene terephthalate, acrylonitrile and the like and epoxyacrylate and urethane acrylate reactive resins (ionizing radiationcurable resin and the like).

The thickness of the base material layer 16 is not particularly limitedbut is preferably equal to or more than 25 μm but equal to or less than300 μm. When the thickness of the base material layer 16 does not fallwithin this range, a problem is likely to occur in processing. Forexample, when the base material layer 16 is excessively thin, a creaseis more likely to occur. Moreover, when the base material layer 16 isexcessively thick, it is difficult to perform winding in an intermediateprocess.

The light deflection layer 17 is a layer that can diffuse light enteringthe light deflection layer 17 through one surface side (as will bedescribed later, in particular, light entering the light deflectionlayer 17 in a direction from obliquely above to down) and emit itthrough the other surface side. The light deflection layer 17 is shapedto have a cross section shown in FIG. 3 and extend from the back side ofthe plane of the figure to the front side. Specifically, in the crosssection in FIG. 3, the light deflection layer 17 includes lightdeflection portions 19 in which a cross section formed between atrapezoidal light transmission portion 18 and the adjacent lighttransmission portion 18 is formed within a concave portion of thetrapezoids. In the present embodiment, the light transmission portions18 on the side of the base material layer 16 are coupled with eachother. The light transmission portion 18 and the light deflectionportion 19 having the cross section extend in one direction (in thepresent embodiment, the horizontal direction) of the sheet surface, anda plurality of light transmission portions 18 and light deflectionportions 19 are aligned in a direction (in the present embodiment, thevertical direction) different from the one direction.

Any part of the light deflection layer 17 may contain an absorptionagent that can absorb at least one of an infrared ray, an ultravioletray and visible light. In particular, an infrared absorption agent iscontained, and thus when it is in summer with the solar altitude high,it is cool because infrared rays are more likely to be absorbed by thelight deflection layer whereas when it is in winter with the solaraltitude low, it is warm because infrared rays are unlikely to beabsorbed by the light deflection layer, with the result that it ispossible to achieve a comfortable indoor environment.

The light transmission portion 18 is a part that transmits light, andthe surface of the light transmission portion 18 on the side of the basematerial layer 16 and the surface (the surface on the side of theprotective layer 21) on the opposite side are preferably formed parallelto each other. Thus, as will be described later, when the daylightingpanel 10 is applied to the window 2, scenery on the outdoor side is moreeasily seen from the indoor side. Preferably, the light transmissionportion 18 transmits light without the light scattered. In this way, theease with which scenery on the back surface side is seen is enhanced.Here, the “transmits light without the light scattered” means that thepart is formed without the intentional addition of a material forscattering the light or the like, and it is allowed that the light isinevitably scattered when the light is in the process of passing throughthe material.

The material of the light transmission portion 18 may be the same asthat of the base material layer 16 or may be different from that of thebase material layer 16. However, since a refractive index differencebetween the both is more likely to cause light to be deflected in theirinterface, it is preferable that the same material be used or thatdifferent materials having a low refractive index difference or norefractive index difference be used.

When the light transmission portion 18 and the base material layer 16are formed of the same material, it is possible to integrally form thebase material layer 16 and the light transmission portion 18. Even whenthe light transmission portion 18 and the base material layer 16 areformed of different materials or when the light transmission portion 18and the base material layer 16 are formed of the same material, the basematerial layer 16 and the light transmission portion 18 may beseparately formed and stacked in layers with a known means.

A specific example of a method of forming the light transmission portion18 will be described later.

Examples of the material of the light transmission portion 18 include atransparent resin that has, as main ingredients, one or more of acrylic,styrene, polycarbonate, polyethylene terephthalate, acrylonitrile andthe like and epoxy acrylate and urethane acrylate reactive resins(ionizing radiation curable resin and the like).

The light transmission portions 18 are aligned in a predetermineddistance in a direction along the sheet surface. Hence, between theadjacent light transmission portions 18, the concave portion having atrapezoidal cross section is formed. The concave portion is a groovethat has a trapezoidal cross section having a lower base on the side ofthe upper base of the light transmission portion 18 and an upper base onthe side of the lower base of the light transmission portion 18, and thelight deflection portions 19 is formed by filling this portion with anecessary material described later. In other words, in the cross sectionshown in FIG. 3, the light transmission portion 18 is an element thathas a trapezoidal cross section having the lower base on the surface onthe side of the base material layer 16 and the upper base shorter thanthe lower base on the opposite side.

The light deflection portion 19 is a part that deflects the incominglight, and in the present embodiment, is formed to diffuse and reflectand then deflect the incoming light. The light deflection portion 19described above can be formed by filling the concave portion between theadjacent light transmission portions 18 with, for example, the followingmaterial. In the present embodiment, the material of the lightdeflection portion 19 is preferably cryptic, and examples thereofinclude white pigments and silver pigments. Examples of the whitepigment include metal oxides such as a titanium oxide, a titaniumdioxide, a magnesium oxide and a zinc oxide. On the other hand, examplesof the silver pigment include metals such as aluminum and chromium.

In order to easily diffuse and reflect light in the interface betweenthe light deflection portion 19 and the light transmission portion 18,the interface between the light transmission portion 18 and the lightdeflection portion 19 may be formed into a mat surface.

As described above, the light deflection portion 19 is formed in theconcave portion between the adjacent light transmission portions 18, andits shape is along the concave portion. Hence, in the presentembodiment, the light deflection portion 19 has a substantiallytrapezoidal cross section having the short upper base on the side of thebase material layer 16 and the long lower base on the side of theprotective layer 21, and has oblique sides between them. The obliqueside forms the interface with the light transmission portion 18, and isthe common oblique side.

An angle θ₁ of the oblique side in the cross section of the lightdeflection portion 19 (the light transmission portion 18) is preferablyequal to or more than 0 degrees but equal to or less than 20 degreeswith respect to the normal to the sheet surface. When the lightdeflection portion 19 is formed such that θ₁ is less than 0 degrees(this means that in the cross section shown in FIG. 3, the width of thelight deflection portion 19 on the side of the protective layer 21 isshorter than that on the side of the base material layer 16), it isdifficult to produce a mold used for forming the light deflection layer17 as described later, and a problem is likely to occur in the moldrelease even if the mold is produced. On the other hand, when θ₁ isexcessively large, it is difficult to increase the aspect ratio of theopening width (in the cross section shown in FIG. 3, the width of thelight deflection portion 19 on the side of the protective layer 21) tothe height (the size in the direction of thickness of the lightdeflection layer 17), with the result that it is difficult to obtain adesired effect described later by the light deflection layer 17.

The pitch with which the light deflection portions 19 are aligned is notparticularly limited but is preferably equal to or more than 10 μm butequal to or less than 200 μm, and is more preferably equal to or morethan 100 μm but equal to or less than 200 μm. When the pitch of thelight deflection portion 19 is excessively narrow, it is difficult toobtain the desired effect described later by the light deflection layer17, and an image transmitted through the light transmission portion 18is disadvantageously likely to be formed into shape of a rainbow by adiffraction phenomenon. When the pitch of the light deflection portion19 is excessively wide, it is disadvantageously likely that it isdifficult to form the light deflection portion 19 and that a problemoccurs in the release and the processing of the mold when the lightdeflection layer 17 is produced as described later. The opening width ofthe light deflection portion 19 (in the cross section shown in FIG. 3,the width on the side of the protective layer 21) is not particularlylimited but is preferably equal to or more than 5 μm but equal to orless than 150 μm. When the opening width of the light deflection portion19 is excessively narrow, it is difficult to obtain the desired effectdescribed later by the light deflection layer 17. When the opening widthof the light deflection portion 19 is excessively wide, it isdisadvantageously likely that it is difficult to form the lightdeflection portion 19 and that a problem occurs in the release and theprocessing of the mold when the light deflection layer 17 is produced asdescribed later.

The thickness of the light deflection layer 17 is not particularlylimited but is preferably equal to or more than 50 μm but equal to orless than 300 μm. When the light deflection layer 17 is excessivelythin, it is likely that it is difficult to obtain the desired effectdescribed later and to perform fine processing (such as the formation ofthe light deflection portion 19). When the light deflection layer 17 isexcessively thick, it is disadvantageously likely that a problem occursin the processing such as the release of the mold when the lightdeflection layer 17 is produced as described later.

In the present invention, the shapes of the light transmission portionand the light deflection portion are not limited to the form shown inFIG. 3. Hence, in a cross section corresponding to the cross sectionshown in FIG. 3, the light transmission portion may be rectangular, anda portion corresponding to the oblique side of the trapezoid describedabove may be formed in the shape of a curve (the tangent of the curvepreferably has the same condition as θ₁ described above at each portion)or a polygonal line (each line of the polygonal line preferably has thesame condition as θ₁ described above).

The adhesive layer 20 is a layer that attaches the protective layer 21to the side of the light deflection layer 17 opposite to the basematerial layer 16, and various types of layers having such a functioncan be used. The material used for the adhesive layer 20 is notparticularly limited but the same material as the adhesive layer 12 canbe used. The preferable thickness of the adhesive layer 20 is the sameas the adhesive layer 12.

The protective layer 21 is a layer that pairs with the base materiallayer 16 and that is arranged to sandwich the light deflection layer 17,and has the function of protecting the light deflection layer 17together with the base material layer 16. As long as the protectivelayer 21 has such a function, its material is not particularly limited,and for example, the protective layer 21 can be formed of the samematerial as the base material layer 16.

The hard coat layer 22 is a layer that, in order to protect the surface,is provided closest to the surface in the daylighting panel 10 on theopposite side of the panel 11. The hard coat layer 22 can be formed as atransparent resin layer, and, in terms of resistance of scratches andsurface contamination, is preferably formed as a cured resin layerobtained by curing a curable resin.

Specifically, an ionizing radiation curable resin, a known curable resinor the like is preferably adopted as necessary according to requiredperformance. Examples of the ionizing radiation curable resin include anacrylate resin, an oxetane resin and a silicone resin. For example, theacrylate ionizing radiation curable resin is formed of: a (meth) acrylicacid ester monomer such as a monofunctional (meth) acrylate monomer, abifunctional (meth) acrylate monomer or a three or more functional(meth) acrylate monomer; a (meth) acrylic acid ester oligomer such as aurethane (meth) acrylate, an epoxy (meth) acrylate, a polyester (meth)acrylates; and a (meth) acrylic acid ester prepolymer. Furthermore,examples of the three or more functional (meth) acrylate monomer includea trimethylolpropane tri(meth) acrylate, a pentaerythritol tetra(meth)acrylate and a dipentaerythritol hexa(meth) acrylate.

The function of enhancing contamination resistance may be added to thehard coat layer 22. This can be achieved by adding, for example, asilicone compound or a fluorine compound. Furthermore, as anotherfunction, the hard coat layer 22 may have the function of enhancing theantistatic characteristic or the function of enhancing water repellency.As the material that can be used for enhancing the antistaticcharacteristic, in an electrically conductive type, there are PEDOT-PSS(PEDOT (poly (3,4-ethylenedioxythiophene); 3,4-ethylenedioxy thiophenepolymer) and PSS (poly(styrenesulfonate); styrene sulfonic acid polymer)are present together) or the like. In an ionic conductive type, thereare lithium salts and the like. As the material that can be used forenhancing the water repellency, there is a fluorine compound or thelike.

The daylighting panel 10 described above can be manufactured as follows,for example.

The daylighting panel 10 can be manufactured by adhering the daylightingsheet 15 to the panel 11 with the adhesive layer 12. For example, thedaylighting sheet 15 is manufactured as follows.

The light deflection layer 17 is first formed by a method using a moldroll. Specifically, the mold roll is prepared in which on the outercircumferential surface of a cylindrical roll, projections and recessesthat can transfer the light transmission portion 18 of the lightdeflection layer 17 are prepared. Then, between the mold roll and a niproll arranged opposite it, the base material that is the base materiallayer 16 is inserted. Here, preferably, on one surface of the basematerial, the adhesive layer 12 is previously formed. Then, while thecomposition of the light transmission portion 18 is being suppliedbetween the surface of the base material on the side where the adhesivelayer 12 is not arranged and the mold roll, the mold roll and the niproll are rotated. Thus, the recess portions of the projections andrecesses formed on the surface of the mold roll are filled with thecomposition of the light transmission portion 18, and thus thecomposition is formed along the shape of the surface of the projectionsand recesses of the mold roll.

Here, as the composition of the light transmission portion 18, thecomposition described above is preferably used, and more specifically,the composition is as follows. That is, a photo-curable resincomposition obtained by mixing a reactive diluent monomer (M1) and aphotopolymerization initiator (I1) to a photo-curable prepolymer (P1)can be used.

Examples of the photo-curable prepolymer (P1) include epoxy acrylate,urethane acrylate, polyether acrylate, polyester acrylate and polythiolprepolymers.

Examples of the reactive diluent monomer (M1) include vinylpyrrolidone,2-ethylhexyl acrylate, β-hydroxyethyl acrylate and tetrahydrofurfurylacrylate.

Examples of the photopolymerization initiator (I1) includehydroxybenzoyl compounds (such as2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-hydroxy cyclohexyl phenylketone and benzoin alkyl ether), benzoylformate compounds (such asmethyl benzoyl formate), thioxanthone compound (such asisopropylthioxanthone), benzophenones (such as benzophenone), phosphoricacid ester compounds (such as 1,3,5-trimethyl benzoyl diphenyl phosphineoxide, bis (2,4,6-trimethyl benzoyl)-phenyl phosphine oxide) and benzyldimethyl ketal. Selection is arbitrarily made among them in terms of anapplication device for curing the photo-curable resin composition andthe curability of the photo-curable resin composition. In order toprevent the light transmission portion 18 from being colored,2-hydroxy-2-methyl-1-phenylpropan-1-one, or 1-hydroxy cyclohexyl phenylketone and bis (2,4,6-trimethyl benzoyl)-phenyl phosphine oxide ispreferably used.

One type of the photo-curable prepolymer (P1), the reactive diluentmonomer (M1) and the photopolymerization initiator (I1) can be used ortwo types or more thereof can be combined and used.

Light is applied from the base material side by a light applicationdevice to the composition of the light transmission portion 18 that issandwiched between the mold roll and the base material and that fillsthat portion. Thus, it is possible to cure the composition of the lighttransmission portion 18 and fix its shape. With a mold release roll, thebase material layer 16 and the molded light transmission portion 18 arereleased from the mold roll.

Then, the recess portion of the light transmission portion 18 is filledwith the composition of the light deflection portion 19, and thecomposition is cured, and thus it is possible to form the lightdeflection portion 19. Specifically, the recess portion of the lighttransmission portion 18 is excessively filled with the composition ofthe light deflection portion 19, and the excessive composition isscraped off with a blade to adjust the amount of composition, with theresult that the recess portion is filled with the composition. Then, thecomposition filling the recess portion is cured with an appropriatemethod.

In this way, it is possible to form the light deflection layer 17 on thebase material layer 16.

On the other hand, a stack member in which the hard coat layer 22 isstacked on one surface of the protective layer 21 and the adhesive layer20 is stacked on the other surface is prepared, and they are stackedsuch that the adhesive layer 20 of the stack member is in contact withthe light deflection layer 17. When the adhesive layer 20 is formed ofan ultraviolet curable resin, a photo-curable resin or the like,ultraviolet rays or light is preferably applied to cure the adhesivelayer 20 after the stacking.

The daylighting sheet 15 produced as described above is adhered to thepanel 11 with the adhesive layer 12 to form the daylighting panel 10. Inthe daylighting panel 10, instead of the adhesive layer 12, anabsorption agent that can absorb at least one of an infrared ray, anultraviolet ray and visible light may be contained in any one of thelayers described above.

Then, main optical paths in a case where the windows 2 are formed withthe daylighting panels 10 and they are arranged in the opening portionsof the building 1 will be described. Schematic examples of the opticalpath are shown in FIG. 3. The examples of the optical path areschematically shown, and the degrees of refraction and reflection andthe like are not exactly shown.

Outside light L31 applied to the daylighting panel 10 in a directionfrom obliquely above to down from which sunlight is assumed to beapplied passes through the panel 11, the adhesive layer 12 and the basematerial layer 16 and reaches the light deflection portion 19 of thelight deflection layer 17. The outside light L31 that has reached thelight deflection portion 19 is deflected by the light deflection portion19. In the present embodiment, the outside light L31 is deflected bybeing diffused and reflected. Then, the defused and reflected lightpasses through the adhesive layer 20, the protective layer 21 and thehard coat layer 22, and enters the indoor side. Here, since the lightentering the indoor side is deflected upwardly and is simultaneouslydiffused, it is possible to prevent the outside light from beingdirectly applied, and furthermore, the outside light illuminates a widerange of the indoor side space.

Illustration is more specifically shown in FIG. 4. FIG. 4 is a diagramof one light deflection portion 19 illustrating the diffusion andreflection. Outside light L41, outside light L42 and outside light L43reached the light deflection portion 19 are, for example, repeatedlyreflected off light-reflecting substances contained in the lightdeflection portion 19, are emitted in different directions and arethereby diffused and deflected.

In the daylighting panel 10 including the daylighting sheet 15 asdescribed above, since at the time of the deflection described above, itis possible to reflect the outside light toward the indoor side and takein it without the outside light being actively absorbed by the lightdeflection portion 19, it is possible to efficiently take in the light.

On the other hand, when the outdoor side is seen from the indoor side,an observer's line of sight corresponds to light L32 of FIG. 3. In otherwords, it is possible to observe the outdoor side through the surface onthe side of the base material layer 16 of the light transmission portion18 parallel to the panel 11 and the opposite side surface. Since in thispart, a high degree of refraction is not performed in the interface, itis possible to clearly see scenery on the outdoor side.

As described above, with the daylighting panel 10, it is possible toefficiently take outside light into the room and relatively clearly seeoutside scenery from the indoor side. Moreover, since the lightdeflection layer 17 is sandwiched between the base material layer 16 andthe protective layer 21, it is possible to enhance the durability.

FIG. 5 is a diagram illustrating a second embodiment, is across-sectional view schematically showing the configuration of thelayers of a daylighting panel 30 and corresponds to FIG. 3. In thedaylighting panel 30, portions having the same configuration as in thedaylighting panel 10 are identified with the same symbols, and theirdescription will not be repeated.

The daylighting panel 30 includes the panel 11, the adhesive layer 12, adaylighting sheet 35. The daylighting sheet 35 also includes the basematerial layer 16, a light deflection layer 37, the adhesive layer 20,the protective layer 21 and the hard coat layer 22. The daylightingpanel 30 differs from the daylighting panel 10 in that, instead of thelight deflection layer 17 of the daylighting panel 10, the lightdeflection layer 37 is applied. In the other respects, the daylightingpanel 30 is the same as the daylighting panel 10.

The daylighting panel 30 differs from the daylighting panel 10 in thatlight is diffused and reflected by the light deflection portion 19 ofthe light deflection layer 17 included in the daylighting panel 10whereas in the daylighting panel 30, light is transmitted and diffusedby the light deflection portion 39 of the light deflection layer 37 andis thereby deflected. The light deflection portion 39 is formed in theconcave portion between the light transmission portions 18 as in thelight deflection portion 19. Hence, the shape of the light deflectionportion 39 is the same as that of the light deflection portion 19 butthe material with which this portion is filled is different from that ofthe light deflection portion 19.

Specifically, the material that transmits and diffuses the light reachedthe light deflection portion 39 is arranged. As the material of thelight deflection portion 39, a material obtained by mixing a transparentbinder resin with a transparent diffusing agent whose refractive indexdiffers from that of the binder resin is preferably used. As thediffusing agent, for example, there are cross-linked particles obtainedby polymerizing monomers which mainly include (meth) acrylic acid esterand styrene. As the specific example of the cross-linked particles,there is Ganz Pearl made by AICA Kogyo Co., Ltd. In the cross-linkedparticles described above, the refractive index can be controlled bychanging the mixing ratio of acrylic acid ester and styrene. Forexample, it is possible to set the refractive index at about 1.49 byincreasing the acrylic ratio, and it is possible to set the refractiveindex at about 1.59 by increasing the styrene ratio. As the diffusingagent, urethane cross-linked particles can also be used. As the specificexample of the urethane cross-linked particles, there is Art Peral madeby Negami Chemical Industrial Co., Ltd. As the diffusing agent, hollowparticles can be used.

Then, main optical paths in a case where the windows are formed with thedaylighting panels 30 and they are arranged in the opening portions ofthe building will be described. Schematic examples of the optical pathare shown in FIG. 5.

Outside light L51 applied to the daylighting panel 30 from in adirection from obliquely above to down from which sunlight is assumed tobe applied passes through the panel 11, the adhesive layer 12 and thebase material layer 16 and reaches the light deflection portion 39 ofthe light deflection layer 37. The outside light L51 that has reachedthe light deflection portion 39 enters the light deflection portion 39and passes through the light deflection portion 39 and is simultaneouslydiffused by the above-described configuration of the light deflectionportion 39. The light that has passed through the light deflectionportion 39 as described above thereafter passes through the adhesivelayer 20, the protective layer 21 and the hard coat layer 22, and entersthe indoor side. Here, since the light entering the indoor side isdefused and deflected, it is possible to prevent the outside light frombeing directly applied, and the outside light can illuminate a widerange of the indoor side space.

Here, since with the daylighting panel 30, it is possible to take theoutside light into the indoor side without the outside light beingactively absorbed by the light deflection portion 39, it is possible toefficiently take in the light.

On the other hand, when the outdoor side is seen from the indoor side,the observer's line of sight is the same as in the daylighting panel 10,and thus it is possible to relatively clearly see scenery on the outdoorside.

As described above, with the daylighting panel 30, it is possible toefficiently take outside light into the indoor side and relativelyclearly see outside scenery from the indoor side. Moreover, since thelight deflection layer 37 is sandwiched between the base material layer16 and the protective layer 21, it is possible to enhance thedurability.

FIG. 6 is a diagram illustrating a third embodiment, is across-sectional view schematically showing the configuration of thelayers of a daylighting panel 40 and corresponds to FIG. 3. In FIG. 6,portions having the same configuration as in FIG. 3 are identified withthe same symbols, and their description will not be repeated.

The daylighting panel 40 includes the panel 11, the adhesive layer 12and a daylighting sheet 45 that is adhered to the panel 11 with theadhesive layer 12. The daylighting sheet 45 also includes the lightdeflection layer 17, the base material layer 16 and the hard coat layer22.

Although in the daylighting panels 10 and 30 described above, the lightdeflection layers 17 and 37 are sandwiched between the base materiallayer 16 and the protective layer 21, in the daylighting panel 40, thelight deflection layer 17 is sandwiched between the panel 11 and thebase material layer 16. Even in the present embodiment, as with thedaylighting panels 10 and 30, it is possible to enhance the durability.With the daylighting panel 40, since it is possible to simplify theconfiguration of the layers as compared with the daylighting panels 10and 30, it is possible to manufacture the daylighting panel 40 at lowcost.

Since in the daylighting panel 40, such a configuration is adopted, thelight deflection layer 17 is arranged on the side of the panel 11, andthe base material layer 16 is on the side of the hard coat layer 22 ascompared with the light deflection layer 17. Hence, as is obvious fromcomparison between FIGS. 3 and 6, in the daylighting panel 40, the lighttransmission portion 18 and the light deflection portion 19 are arrangedsuch that they are reversed.

Even in the daylighting panel 40 described above, as with thedaylighting panel 10, it is possible to efficiently take light into theindoor side, and to clearly see scenery on the outdoor side when theoutdoor side is seen from the indoor side. Although in this example, thelight deflection layer 17 is applied, the light deflection layer 37 maybe used instead.

Furthermore, in the present embodiment, the light deflection layer 17can be configured as follows. FIG. 7 shows a diagram of an enlarged partof the light deflection layer 17. As described above, between two lightdeflection portions 19, the light transmission portion 18 is arranged.As shown in line VIIa of FIG. 7, a line corresponding to the diagonalline of the light transmission portion 18 can be defined. Morespecifically, in the sides of the adjacent light deflection portions 19opposite each other, the line VIIa connecting an indoor side end portionof the side of the light deflection portion 19 arranged below and anoutdoor side end portion of the side of the light deflection portion 19arranged adjacently above is assumed to be a prospective line, and anangle of 90 degrees or less of the angles formed between the prospectiveline Vila and the horizontal surface is assumed to be a prospectiveangle θ_(a). In the present embodiment, the angle θ_(a) is preferably apredetermined value.

In the leg portions of the trapezoidal cross section of the lightdeflection portion 19, as is obvious from FIG. 7, the leg portion on theupper side is inclined at θ_(U) with respect to the horizontal surface(the normal to the sheet surface of the daylighting panel 40), and theleg portion on the lower side is likewise inclined at θ_(D).

A preferable value of the prospective angle θ_(a) will be describedbased on main optical paths. Optical path examples necessary for thedescription will be shown, as necessary, in drawings below.

FIG. 8 shows light L_(S1) from the sun as one optical path example. Asis obvious from FIG. 8, the light L_(S1) is applied to the daylightingpanel 40 at an elevation angle (an angle formed from the horizontalsurface) θ_(S1) based on the altitude of the sun at that time. While thelight L_(S1) entering the daylighting panel 40 passes through thedaylighting panel 40, the light L_(S1) travels through the lighttransmission portion 18 of the light deflection layer 17. Within thelight transmission portion 18, when it is assumed that the refractiveindex of the light transmission portion is N_(P), and the refractiveindex of the outdoor side is N_(O), the light L_(S1) travels at asunlight travel angle θ_(P1) expressed in formula (1).

$\begin{matrix}{\left\lbrack {{Formula}\mspace{14mu} 1} \right\rbrack\mspace{619mu}} & \; \\{\theta_{P\; 1} = {\sin^{- 1}\left( {\frac{N_{0}}{N_{P}}\sin\;\theta_{S\; 1}} \right)}} & (1)\end{matrix}$

When the sunlight traveling at the sunlight travel angle θ_(P1) reachesthe interface between the light transmission portion 18 and the lightdeflection portion 19, as described above, the sunlight can be diffusedand reflected. In this way, the sunlight is deflected, and thus it ispossible to reduce direct light that causes glare.

As described above, with the daylighting panel 40, regardless of theprospective angle θ_(a), sunlight is efficiently taken into the room,and simultaneously, it is possible to reduce at least part of the directlight. However, in order to more effectively apply sunlight to the lightdeflection portion 19, scatter the sunlight and emit the sunlight to theindoor side, it is possible to specify that the prospective angle θ_(a)falls within a predetermined angle range. This will be described indetail below.

In FIG. 9, an illustrative diagram is shown. Here, an elevation angleθ_(SH), the elevation angle which can be set when the culminationaltitude is the highest in one year will be considered. Specifically,when sunlight enters the daylighting panel 40 at the elevation angleθ_(SH) when the culmination altitude is the highest at least in oneyear, the prospective angle θ_(a) can be specified so that all directlight form the sunlight is made to reach the light deflection portion19. As is obvious from FIG. 9, in order for the light L_(SH) enteringthe daylighting panel 40 at the elevation angle θ_(SH) to reach thelight deflection portion 19 without fail, the condition under which thelight L_(SH) travels along the prospective line within the lighttransmission portion 18 is necessary. In other words, a sunlight travelangle θ_(PH) within the light transmission portion 18 is preferablyequal to the prospective angle θ_(a). Hence, this is expressed, when itis assumed that the refractive index of the air is N_(O), and therefractive index of the light transmission portion is N_(P), by thefollowing formula (2) that is a relational expression between therefractive index and the entrance angle.

$\begin{matrix}{\left\lbrack {{Formula}\mspace{14mu} 2} \right\rbrack\mspace{619mu}} & \; \\{\theta_{P\; H} = {{\sin^{- 1}\left( {\frac{N_{0}}{N_{P}}\sin\;\theta_{S\; H}} \right)} = \theta_{a}}} & (2)\end{matrix}$

The prospective angle θ_(a) is formulated from formula (2) so as tosatisfy formula (3) below, and thus it is possible to make all directlight from sunlight reach the light deflection portion 19 when thesunlight enters the daylighting panel 40 at the elevation angle θ_(S11)when the culmination altitude is the highest at least in one year.

$\begin{matrix}{\left\lbrack {{Formula}\mspace{14mu} 3} \right\rbrack\mspace{619mu}} & \; \\{\theta_{a} \leqq {\sin^{- 1}\left( {\frac{N_{0}}{N_{P}}\sin\;\theta_{S\; H}} \right)}} & (3)\end{matrix}$

Since the elevation angle θ_(SH) is an elevation angle in the positionwhere the culmination altitude is the highest in a predetermined place,in the predetermined place, no elevation angle equal to or more than theelevation angle θ_(SH) is present. Hence, in order for all sunlight at apredetermined elevation angle less than the elevation angle θ_(SH) to bealso made to likewise reach the light deflection portion 19, formula (1)is satisfied, and furthermore, with consideration given to thepredetermined elevation angle instead of θ_(SH) in formulas (2) and (3),it is likewise possible to obtain the necessary value of the prospectiveangle θ_(a).

For example, when it is desired that direct sunlight at an elevationangle equal to or more than an elevation angle θ_(SM) between theelevation angle θ_(SH) when the culmination altitude is the highest inone year and an elevation angle θ_(SL) when the culmination altitude isthe lowest in one year is made to reach the light deflection portion,the prospective angle θ_(a) is preferably formed so as to satisfyformulas (3) and (4).

$\begin{matrix}{\left\lbrack {{Formula}\mspace{14mu} 4} \right\rbrack\mspace{619mu}} & \; \\{\theta_{a} \leqq {\sin^{- 1}\left( {\frac{N_{0}}{N_{P}}\sin\;\theta_{S\; M}} \right)}} & (4)\end{matrix}$

For example, in order to make the prospective angle θ_(a) equal to thepredetermined angle as described above, the pitch in the lightdeflection portion, the angles (θ_(U) and θ_(D) in FIG. 7) of the legportions of the light deflection portion and the size in the directionof thickness of the light deflection portion (the left/right directionof FIG. 7) are changed. By using them singly or combining them, it ispossible to adjust the prospective angle θ_(a) to the predeterminedangle.

As described above, when the prospective angle θ_(a) is decreased, evenif the culmination altitude is different depending on the season, andthe elevation angle is changed as the height of the sun is moved in oneday, it is possible to make a larger amount of sunlight reach the lightdeflection portion, to totally reflect or scatter and reflect it andsupply it to the indoor side.

On the other hand, the prospective angle θ_(a) is decreased, and thusthe light deflection layer 17 may become thick or the light transmissionportion may become small. Thus, visual recognition in the outdoor sideis likely to be reduced. Although the lower limit of the prospectiveangle θ_(a) is not particularly limited in terms of what has beendescribed, for example, as shown in FIG. 10, the lower limit of theprospective angle θ_(a) may be determined so that all direct sunlight atthe elevation angle θ_(SL) when the culmination altitude is the lowestin one year is made to reach the light deflection portion 19. Anillustrative diagram will be shown in FIG. 10.

Since the basic idea is the same as in the calculation of formulas (2)and (3), as is obvious from FIG. 10, sunlight L_(SL) at the elevationangle θ_(SL) preferably travels along the prospective line, with theresult that it is possible to obtain formula (5).

$\begin{matrix}{\left\lbrack {{Formula}\mspace{14mu} 5} \right\rbrack\mspace{619mu}} & \; \\{\theta_{PL} = {{\sin^{- 1}\left( {\frac{N_{0}}{N_{P}}\sin\;\theta_{S\; L}} \right)} = \theta_{a}}} & (5)\end{matrix}$

Here, θ_(PL) is the sunlight travel angle of the light transmissionportion at the time of the elevation angle θ_(SL). Hence, it is possibleto obtain formula (6) from the intension to determine formulas (3) and(5).

$\begin{matrix}{\left\lbrack {{Formula}\mspace{14mu} 6} \right\rbrack\mspace{619mu}} & \; \\{{\sin^{- 1}\left( {\frac{N_{0}}{N_{P}}\sin\;\theta_{S\; L}} \right)} \leqq \theta_{a} \leqq {\sin^{- 1}\left( {\frac{N_{0}}{N_{P}}\sin\;\theta_{S\; H}} \right)}} & (6)\end{matrix}$

Here, a more specific example will be described. With considerationgiven to Japan, the elevation angle (θ_(SH)) when the culminationaltitude is the highest in one year and the elevation angle (θ_(SL))when the culmination altitude is the lowest in one year in Sapporo,Tokyo and Okinawa are shown in table 1.

TABLE 1 θ_(SH) θ_(SL) Sapporo 70.5° 23.5° Tokyo 78.0° 31.0° Okinawa87.5° 40.5°

Based on table 1, the range of θ_(a) in Japan may be set as shown informulas (7) and (8).

$\begin{matrix}{\left\lbrack {{Formula}\mspace{14mu} 7} \right\rbrack\mspace{619mu}} & \; \\{\theta_{a} \leqq {\sin^{- 1}\left( {\frac{N_{0}}{N_{P}}\sin\; 70.5{^\circ}} \right)}} & (7) \\{\left\lbrack {{Formula}\mspace{14mu} 8} \right\rbrack\mspace{619mu}} & \; \\{{\sin^{- 1}\left( {\frac{N_{0}}{N_{P}}\sin\; 40.5{^\circ}} \right)} \leqq \theta_{a} \leqq {\sin^{- 1}\left( {\frac{N_{0}}{N_{P}}\sin\; 70.5{^\circ}} \right)}} & (8)\end{matrix}$

According to formula (7), all direct sunlight from the culminationaltitude in the summer solstice over the substantially entire region ofJapan can be made to each the light deflection portion. Moreover,according to formula (8), it is possible to make a large amount ofsunlight reach the light deflection portion with higher visualrecognition.

FIG. 11 is a diagram illustrating a fourth embodiment, is across-sectional view schematically showing the configuration of thelayers of a daylighting panel 50 and corresponds to FIG. 3. In FIG. 11,portions having the same configuration as in FIG. 3 are identified withthe same symbols, and their description will not be repeated.

The daylighting panel 50 includes the panel 11, the adhesive layer 12and a daylighting sheet 55 that is adhered to the panel 11 with theadhesive layer 12. The daylighting sheet 55 also includes a lightdeflection layer 57, the base material layer 16 and the hard coat layer22.

The light deflection layer 57 includes a light transmission portion 58and a light deflection portion 59. The light transmission portion 58 hasa cross section shown in FIG. 11, and is arranged so as to extend in onedirection (the horizontal direction in the position arranged in thebuilding 1) along the surface of the base material layer 16, and aplurality of light transmission portions 58 are aligned in apredetermined distance in a direction different from the one directionalong the surface of the base material layer 16 (the vertical directionin the position arranged in the building 1). In the present embodiment,adjacent light transmission portions 58 are integrally coupled at theend portions on the side of the base material layer 16.

On the other hand, the light deflection portion 59 is arranged betweenthe adjacent light transmission portions 58.

FIG. 12 shows a diagram of an enlarged part of the light deflectionlayer 57.

The light transmission portion 58 is a part that transmits light, andthe surface of a part of the light deflection layer 57 where the lighttransmission portion 58 is arranged on the side of the base materiallayer 16 and the surface (the surface on the side of the adhesive layer12) on the opposite side are formed parallel to each other. Preferably,the light transmission portion 58 transmits light without the lightscattered. In this way, the ease with which scenery on the back surfaceside is seen is enhanced. Here, the “transmits light without the lightscattered” means that the part is formed without the intentionaladdition of a material for scattering the light or the like, and it isallowed that the light is inevitably scattered when the light is in theprocess of passing through the material.

In the present embodiment, in the cross section shown in FIGS. 11 and12, the light transmission portion 58 has a substantially trapezoidalcross section between two light deflection portions 59 with a shortupper base on the outdoor side and a long lower base on the indoor side,and a side that forms an interface with the light deflection portion 59is a leg portion. However, since the leg portion is shaped along theshape of the light deflection portion 59, which will be described later,the leg portion is not necessarily straight.

The material of the light transmission portion 58 is the same as that ofthe light transmission portion 18 described above.

The light deflection portion 59 is a part that is formed between twoadjacent light transmission portions 58. Specifically, as describedabove, the light transmission portions 58 are aligned in a predetermineddistance in the direction along the sheet surface of the lighttransmission portion 58, and a concave portion having a predeterminedshape is formed between the light transmission portions 58. The concaveportion in the present embodiment is a groove that has a cross-sectionalshape corresponding to the cross-sectional shape of the light deflectionportion 59, and is filled with the material of the light deflectionportion 59 to form the light deflection portion 59. Hence, the lightdeflection portion 59 has the cross-sectional shape based on the concaveportion.

In the present embodiment, the light deflection portion 59 is a partthat can totally reflect and deflect light applied here. Hence, thelight deflection portion 59 is filled with the material whose refractiveindex is lower than that of the light transmission portion 58. Thus,when the light that has entered the light deflection portion 59satisfies total reflection conditions by the refractive index differencebetween the light deflection portion 59 and the light transmissionportion 58 and a relationship of the angle of the light entering theinterface, it is possible to totally reflect and deflect the light here.As will be described in detail later, the deflected light is changed indirection, and for example, the light is applied to the ceiling, andthus it is possible to prevent the light from being directly appliedwithout glare being given. In terms of general versatility of a rawmaterial, the refractive index of the material of the light deflectionportion 59 is preferably equal to or more than 1.49 but equal to or lessthan 1.56, and is more preferably equal to or more than 1.49 but equalto or less than 1.50.

Here, the refractive index difference between the light transmissionportion 58 and the light deflection portion 59 is equal to or more than0.03 but equal to or less than 0.07, and is more preferably equal to ormore than 0.05 but equal to or less than 0.06. When the refractive indexdifference is more than 0 but less than 0.03, if wavelength dispersion(dispersion caused by the difference of total reflection angles due tothe wavelengths) at the time of total reflection occurs, the componentof a long wavelength may not be totally reflected and only the componentof a short wavelength may be totally reflected, with the result that thecolor is likely to be changed. On the other hand, when the refractiveindex difference is more than 0.06, the refractive index of thecomponent of the short wavelength tends to be higher than the refractiveindex of the component of the long wavelength, with the result thatunevenness in the shape of a rainbow is likely to occur remarkably.

Furthermore, in the present embodiment, the light deflection portion 59has a shape as described below. A description will be given withreference to FIG. 12.

In a cross section shown in FIG. 12, the light deflection portion 59 hasa polygonal shape. Among them, in the position where the daylightingpanel 50 is arranged in the building 1, the upper portion side isarranged such that two sides 59 a and 59 b are continuous in anindoor/outdoor direction, and is formed to be convex downward. In otherwords, the side 59 a is arranged on the outdoor side, and the side 59 bis arranged on the indoor side.

In the position shown in FIG. 12, these two sides 59 a and 59 brespectively have, as their inclination angles, different angles θ_(U1)and θ_(U2) with respect to the horizontal surface (the normal to thesheet surface of the daylighting sheet 55). Here, the angles θ_(U1) andθ_(U2) are inclined with their upper portions toward the outdoor side(the side of the sun), and the angle θ_(U1) is assumed to be larger thanthe angle θ_(U2). In this way, with consideration given to the altitudeof the sun different depending on the season and the time, it ispossible to extend the case where it is possible to totally reflect anddeflect the sunlight in the interface between the light transmissionportion 58 and the light deflection portion 59. Hence, the angles θ_(U1)and θ_(U2) are preferably determined in terms of what has been describedabove. A detailed description will be given later using an optical pathexample.

On the other hand, the side 59 d of the lower portion side opposite tothe sides 59 a and 59 b is assumed to have, as its inclination angle, anangle θ_(D1) with respect to the horizontal surface (the normal to thesheet surface of the daylighting sheet 55). The angle θ_(D1) is notparticularly limited but is preferably equal to or more than 0 degreesbut equal to or less than 30 degrees in terms of manufacturing.

FIG. 13 shows cross-sectional shapes of light deflection portionsaccording to variations.

FIG. 13(a) shows an example of a light deflection portion 59′ in whichthe side on the upper portion side is convex downward (that is,concave). In this example, preferably, the inclination angle of atangent at a part closest to the outdoor side is an angle θ_(U1) withrespect to the horizontal surface (the normal to the sheet surface ofthe daylighting sheet 50), and the inclination angle of a tangent at apart closest to the indoor side is an angle θ_(U2) with respect to thehorizontal surface (the normal to the sheet surface of the daylightingsheet 50).

FIG. 13(b) shows an example of a light deflection portion 59″ in whichthe side on the upper portion side is formed with three sides 59″a, 59″cand 59″b as seen sequentially from the outdoor side, and is convexdownward (that is, concave). In this example, preferably, theinclination angle of the side 59″a closest to the outdoor side is anangle θ_(U1) with respect to the horizontal surface (the normal to thesheet surface of the daylighting sheet 50), the inclination angle of theside 59″b closest to the indoor side is an angle θ_(U2) with respect tothe horizontal surface (the normal to the sheet surface of thedaylighting sheet 50) and the inclination angle of the side 59″carranged therebetween is an angle θ_(U2) with respect to the horizontalsurface (the normal to the sheet surface of the daylighting sheet 50),and satisfies an inequality θ_(U2)<θ_(U3)<θ_(U1).

Although here, the example where the light deflection portion is formedwith the three sides 59″a, 59″c and 59″b has been described, the presentinvention is not limited to this configuration, and the light deflectionportion may be formed with a larger number of sides.

Even with the light deflection portions shown in FIGS. 13(a) and 13(b),the same effects as the light deflection portion having the shape shownin FIG. 12 are also achieved. Furthermore, with the shapes shown inFIGS. 13(a) and 13(b), it is possible to reduce the occurrence ofunevenness in the shape of a rainbow caused by wavelength dispersionresulting from total reflection.

An effect in the case where the daylighting sheet 50 is arranged in thebuilding 1 as described above, and the preferable values of the anglesθ_(U1) and θ_(U2) described above will now be described based on mainoptical paths. Optical path examples necessary for the description willbe shown, as necessary, in drawings below.

FIG. 14 shows light L_(S2) from the sun as one optical path example. Asis obvious from FIG. 14, the light L_(S2) is applied to the daylightingpanel 50 at an elevation angle (an angle formed from the horizontalsurface) θ_(S2) based on the altitude of the sun at that time. While thelight L_(S2) entering the daylighting panel 50 passes through thedaylighting panel 50, the light L_(S2) travels through the lighttransmission portion 58 of the light deflection layer 57. Within thelight transmission portion 58, when it is assumed that the refractiveindex of the light transmission portion is N_(P), and the refractiveindex of the outdoor side is N_(O), the light L_(S2) travels at asunlight travel angle θ_(P2) expressed in formula (9).

$\begin{matrix}{\left\lbrack {{Formula}\mspace{14mu} 9} \right\rbrack\mspace{619mu}} & \; \\{\theta_{P\; 2} = {\sin^{- 1}\left( {\frac{N_{0}}{N_{P}}\sin\;\theta_{S\; 2}} \right)}} & (9)\end{matrix}$

When the sunlight traveling at the sunlight travel angle θ_(P2), reachesa part whose inclination angle is θ_(U2) in the interface between thelight transmission portion 58 and the light deflection portion 59, ifthe refractive index difference between the light transmission portion58 and the light deflection portion 59 and a relationship of thesunlight travel angle θ_(P2) are equal to or more than the criticalangle of total reflection, total reflection occurs in the interface asshown in FIG. 14. In this way, the sunlight is deflected, and thus it ispossible to reduce direct light that causes glare.

FIG. 15 shows light L_(S3) from the sun as another optical path example.As is obvious from FIG. 15, the light L_(S3) is applied to thedaylighting panel 50 at an elevation angle (an angle formed from thehorizontal surface) θ_(S3) based on the altitude of the sun at thattime. Here, the angle θ_(S3) is larger than the angle θ_(S2). While thelight L_(S3) entering the daylighting panel 50 passes through thedaylighting panel 50, the light L_(S3) travels through the lighttransmission portion 58 of the light deflection layer 57. Within thelight transmission portion 58, when it is assumed that the refractiveindex of the light transmission portion is N_(P), and the refractiveindex of the outdoor side is N_(O), the light L_(S3) travels at asunlight travel angle θ_(P3) expressed in formula (10).

$\begin{matrix}{\left\lbrack {{Formula}\mspace{14mu} 10} \right\rbrack\mspace{596mu}} & \; \\{\theta_{P\; 3} = {\sin^{- 1}\left( {\frac{N_{0}}{N_{P}}\sin\;\theta_{S\; 3}} \right)}} & (10)\end{matrix}$

In this example, when the sunlight traveling at the sunlight travelangle θ_(P3) reaches a part whose inclination angle is θ_(U1) in theinterface between the light transmission portion 58 and the lightdeflection portion 59, if the refractive index difference between thelight transmission portion 58 and the light deflection portion 59 and arelationship of the sunlight travel angle θ_(P3) are equal to or morethan the critical angle of total reflection, total reflection occurs inthe interface as shown in FIG. 15. Thus, the sunlight travels throughthe light transmission portion 58 at an elevation angle lower than thesunlight travel angle θ_(P3), and furthermore, reaches a part whoseinclination angle arranged on the indoor side is θ_(U2), where thesunlight is totally reflected. In this way, the sunlight is deflected,and thus it is possible to reduce direct light that causes glare.

In other words, in this example, the sunlight is totally reflected twiceat the part whose inclination angle is θ_(U1) and at the part whoseinclination angle is θ_(U2) in the interface between the lighttransmission portion 58 and the light deflection portion 59, and isdeflected, with the result that direct light that causes glare isinhibited.

If the entire inclination angle of the light deflection portion isθ_(U2), since the light L_(S3) enters the light transmission portion atthe elevation angle (sunlight travel angle) θ_(P3), the L_(S3) cannot betotally reflected in the interface between the light deflection portionand the light transmission portion, passes through it and enters theroom as direct light.

On the other hand, with the light deflection portion 59, it is possibleto totally reflect and deflect even the light L_(S3) described abovesuch that the light L_(S3) does not become direct light.

As is obvious from what has been described, with the daylighting sheet50, when the inclination angles θ_(U1) and θ_(U2) have a relationship ofθ_(U1)>θ_(U2), it is possible to totally reflect and deflect at leastpart of the sunlight, such as the light L_(S2) and light L_(S3), whosetravel angles are different and thereby supply it to the indoor side,and it is also possible to eliminate at least part of direct light(so-called direct sunlight) without significantly reducing the amount ofsunlight entering the room. In this way, it is possible to form abrighter and more comfortable indoor space.

Furthermore, in the daylighting sheet 50, as described above, the lighttransmission portion 58 is provided, and the front and back surface ofthe light deflection layer 57 on the parts where the light transmissionportion 58 are to be arranged are formed parallel and smoothly. Thus, asin the example of the other embodiment, it is possible to visuallyrecognize scenery on the outdoor side from the indoor side.

Here, the deflected direction depends on the sunlight travel angle θ_(P)that is an angle at the time of entrance of the interface and theinclination angles θ_(U1) and θ_(U2) of the light deflection portion.Hence, here, the inclination angles θ_(U1) and θ_(U2) are preferablydetermined such that the totally reflected light is finally upward ascompared with the horizontal surface.

As described above, when θ_(U1)>θ_(U2), with the daylighting sheet 50,it is possible to efficiently take sunlight into the room and tosimultaneously eliminate at least part of direct light. However, inorder to more effectively totally reflect sunlight at the lightdeflection portion 59 and deflect and emit the sunlight to the indoorside, it is possible to specify preferable inclination angles θ_(U1) andθ_(U2). A detailed description will be given below.

As is obvious from the optical path example described above, when theelevation angle of the sun is high, the inclination angle θ_(U1) can setan angle at which it is possible to appropriately totally reflect thesunlight entered the daylighting sheet. Thus, for example, it ispossible to set the elevation angle θ_(SH) when the culmination altitudeis the highest in one year. Specifically, since the sunlight travelangle θ_(PH) within the light transmission portion when the elevationangle is set at the elevation angle θ_(SH) is expressed in formula (2)described above, the inclination angle θ_(U1) is set such that the lighttravelling at the angle θ_(PH) can be totally reflected. However, sincethe elevation angle θ_(SH) is different depending on the latitude, it ispossible to specify the range of the inclination angle θ_(U1) byspecifying a range from θ_(SH1) to θ_(SH2) (θ_(SH1)<θ_(SH2)) in apredetermined range (for example, countries and areas) extending overdifferent latitudes. In other words, it is possible to set formula (11)at the preferable range of the inclination angle θ_(U1).

$\begin{matrix}{\left\lbrack {{Formula}\mspace{14mu} 11} \right\rbrack\mspace{599mu}} & \; \\{{\sin^{- 1}\left( {\frac{N_{0}}{N_{P}}\sin\;\theta_{{SH}\; 1}} \right)} \leqq \theta_{U\; 1} \leqq {\sin^{- 1}\left( {\frac{N_{0}}{N_{P}}\sin\;\theta_{{SH}\; 2}} \right)}} & (11)\end{matrix}$

Here, since table 1 holds true for Japan, the inclination angle θ_(U1)preferably falls within the range of formula (12).

$\begin{matrix}{\left\lbrack {{Formula}\mspace{14mu} 12} \right\rbrack\mspace{599mu}} & \; \\{{\sin^{- 1}\left( {\frac{N_{0}}{N_{P}}\sin\; 70.5{^\circ}} \right)} \leqq \theta_{U\; 1} \leqq {\sin^{- 1}\left( {\frac{N_{0}}{N_{P}}\sin\; 87.5{^\circ}} \right)}} & (12)\end{matrix}$

On the other hand, as is obvious from the optical path example describedabove, when the elevation angle of the sun is low, it is possible to setan angle at which it is possible to appropriately totally reflect thesunlight entering the daylighting sheet. Thus, for example, it ispossible to set the elevation angle θ_(SL), the elevation angle whichcan be set when the culmination altitude is the lowest in one year.Specifically, since the sunlight travel angle θ_(PL) within the lighttransmission portion when the elevation angle is set at the elevationangle θ_(SL) is expressed in formula (5) described above, theinclination angle θ_(U2) is set such that the light travelling at theangle θ_(PL) can be totally reflected.

However, since the elevation angle θ_(PL) is different depending on thelatitude, it is possible to specify the range of the inclination angleθ_(U2) by specifying a range from θ_(SL1) to θ_(SL2) (θ_(SL1)<θ_(SL2))in a predetermined range (for example, countries and areas) extendingover different latitudes. Here, since it is difficult to perform themanufacturing when the inclination angle θ_(U2) is less than 0 degrees(inclined oppositely with respect to FIG. 12), the inclination angleθ_(U2) is preferably equal to or more than 0 degrees. In this way, it ispossible to set formula (13) at the preferable range of the inclinationangle θ_(U2).

$\begin{matrix}{\left\lbrack {{Formula}\mspace{14mu} 13} \right\rbrack\mspace{599mu}} & \; \\{{0{^\circ}} \leqq \theta_{U\; 2} \leqq {\sin^{- 1}\left( {\frac{N_{0}}{N_{P}}\sin\;\theta_{{SL}\; 2}} \right)}} & (13)\end{matrix}$

Here, since in Japan, the elevation angle θ_(SL) in Okinawa is 40.5degrees, the inclination angle θ_(U2) preferably falls within a range offormula (14).

$\begin{matrix}{\left\lbrack {{Formula}\mspace{14mu} 14} \right\rbrack\mspace{599mu}} & \; \\{{0{^\circ}} \leqq \theta_{U\; 2} \leqq {\sin^{- 1}\left( {\frac{N_{0}}{N_{P}}\sin\; 40.5{^\circ}} \right)}} & (14)\end{matrix}$

FIG. 16 is a diagram illustrating a fifth embodiment, is a diagram of anenlarged part of a cross section of a light deflection layer 67 includedin the fifth embodiment and corresponds to FIG. 12. Since the presentembodiment is characterized in the cross-sectional shape of the lightdeflection layer 67, only the light deflection layer 67 will bedescribed. The other parts are the same as described above.

The light deflection layer 67 includes a light transmission portion 68and a light deflection portion 69. The light transmission portion 68 hasa cross section shown in FIG. 16, and is arranged so as to extend in onedirection (the horizontal direction in the position arranged in thebuilding 1) along the surface of the base material layer, and aplurality of light transmission portions 68 are aligned in apredetermined distance in a direction different from the one directionalong the surface of the base material layer (the vertical direction inthe position arranged in the building 1). In the present embodiment,adjacent light transmission portions 68 are integrally coupled at theend portions on the side of the base material layer.

On the other hand, the light deflection portion 69 is arranged betweenthe adjacent light transmission portions 68.

The light transmission portion 68 is a part that transmits light, andthe surface of a part of the light deflection layer 67 where the lighttransmission portion 68 is arranged on the side of the base materiallayer 16 (see FIG. 11) and the surface (the surface on the side of theadhesive layer 12, see FIG. 11) on the opposite side are preferablyformed parallel to each other and smoothly. In this way, it is possibleto more easily see scenery on the outdoor side as described above.

In the present embodiment, in the cross section shown in FIG. 16, thelight transmission portion 68 has a substantially trapezoidal crosssection between two light deflection portions 69 with a short upper baseon the outdoor side and a long lower base on the indoor side, and a sidethat forms an interface with the light deflection portion 69 is a legportion. However, since the leg portion is shaped along the shape of thelight deflection portion 69, which will be described later, the legportion is not necessarily straight.

The light deflection portion 69 is a part that is formed between twoadjacent light transmission portions 68. Specifically, as describedabove, the light transmission portions 68 are aligned in a predetermineddistance in the direction along the sheet surface of the lighttransmission portion 68, and a groove-shaped concave portion having apredetermined shape is formed between the light transmission portions68. The concave portion in the present embodiment is a groove that has across-sectional shape corresponding to the cross-sectional shape of thelight deflection portion 69, and is filled with the material of thelight deflection portion 69 to form the light deflection portion 69.Hence, the light deflection portion 69 has the cross-sectional shapebased on the concave portion.

The light deflection portion 69 is a part that can totally reflect anddeflect light applied to the light deflection portion 69. Hence, thelight deflection portion 69 is filled with the material whose refractiveindex is lower than that of the light transmission portion 68. Thus,when the light that has entered the light deflection portion 69satisfies total reflection conditions by the refractive index differencebetween the light deflection portion 69 and the light transmissionportion 68 and a relationship of the angle of the light entering theinterface, it is possible to totally reflect and deflect the light inthe light deflection portion 69. As will be described in detail later,the deflected light is changed in direction, and for example, the lightis applied to the ceiling, and thus it is possible to prevent the lightfrom being directly applied without glare being given. In terms ofgeneral versatility of a raw material, the refractive index of thematerial of the light deflection portion 69 is preferably equal to ormore than 1.49 but equal to or less than 1.56, and is more preferablyequal to or more than 1.49 but equal to or less than 1.50.

Here, the refractive index difference between the light transmissionportion 68 and the light deflection portion 69 is equal to or more than0.03 but equal to or less than 0.07, and is more preferably equal to ormore than 0.05 but equal to or less than 0.06. When the refractive indexdifference is more than 0 but less than 0.03, if wavelength dispersion(dispersion caused by the difference of total reflection angles due tothe wavelengths) at the time of total reflection occurs, the componentof a long wavelength may not be totally reflected and only the componentof a short wavelength may be totally reflected, with the result that thecolor is likely to be changed. On the other hand, when the refractiveindex difference is more than 0.07, the refractive index of thecomponent of the short wavelength tends to be higher than the refractiveindex of the component of the long wavelength, with the result thatunevenness in the shape of a rainbow is likely to occur remarkably.

Furthermore, in the present embodiment, the light deflection portion 69has a shape as described below. A description will be given withreference to FIG. 16.

As described above, the light deflection portion 69 is shaped along theconcave portion between adjacent light transmission portions 68, andhas, in the cross section shown in FIG. 16, an upper portion side 69 aand a lower portion side 69 b. Among them, the upper portion side 69 ais formed to be curved such that the side 69 a is convex upward. In thisway, as described later, the light totally reflected off the side 69 aof the light deflection portion 69 is widely diffused, and thus it ispossible to prevent the light from being concentrated in a narrow range.A detailed description will be given below using an optical pathexample.

As long as the side 69 a is convex upward in the position shown in FIG.16 as described above, the side 69 a is not particularly limited. As theexamples of this, there are an example where the side 69 a is formedwith a polygonal line in which a plurality of straight lines arecontinuous and an example where the side 69 a is formed with a curve.

Preferably, when the side 69 a is curved, as shown in FIG. 16, a tangentin an arbitrary position has an angle θ_(U3) with respect to thehorizontal surface (the normal to the sheet surface of the daylightingsheet), and is inclined such that its upper portion is toward theoutdoor side (the side of the sun), and the angle θ_(U3) in each part ofthe side 69 a is continuously changed from the outdoor side to theindoor side. Thus, it is possible to make the above effects moreremarkable. Although the range of the angle θ_(U3) is not particularlylimited, in a center portion of the light deflection portion 69 in theindoor/outdoor direction, the angle θ_(U3) is preferably more than 0degrees but less than 30 degrees.

On the other hand, the side 69 b of the lower portion side opposite tothe side 69 a is assumed to have, as its inclination angle, an angleθ_(D3) with respect to the horizontal surface (the normal to the sheetsurface of the daylighting sheet). The angle θ_(D3) is not particularlylimited but is preferably equal to or more than 0 degrees but equal toor less than 30 degrees in terms of manufacturing.

A daylighting unit is formed with the daylighting panel having thedaylighting sheet including the light deflection layer 67 describedabove, and is arranged in the opening portion of the building 1 as shownin FIG. 1. Effects in a case where the daylighting sheet is arranged asdescribed above will now be described based on main optical paths.Optical path examples necessary for the description are shown in FIG.16.

FIG. 16 shows light L_(S4) and light L_(S5) from the sun as optical pathexamples. As is obvious from FIG. 16, the light L_(S4) and the lightL_(S5) are two types of light that are applied to different positions ofthe daylighting panel at an elevation angle (an angle formed from thehorizontal surface) based on the altitude of the sun at that time. Whilethe light L_(S4) and the light L_(S5) entering the daylighting panelpass through the daylighting panel 12, the light L_(S4) and the lightL_(S5) travel through the light transmission portion 68 of the lightdeflection layer 67. When the sunlight travelling through the lighttransmission portion 68 reaches the interface between the lighttransmission portion 68 and the light deflection portion 69, if therefractive index difference between the light transmission portion 68and the light deflection portion 69 and a relationship of the sunlighttravel angle are equal to or more than the critical angle of totalreflection, total reflection occurs in the interface as shown in FIG.16. In this way, the sunlight is deflected, and thus it is possible toreduce direct light that causes glare. Here, the light L_(S4) and thelight L_(S5) that were parallel to each other at the time of theentrance reach different positions of the side 69 a of the lightdeflection portion 69. Since the side 69 a is formed to be convex asdescribed above, the light L_(S4) and the light L_(S5) are totallyreflected in different directions. In this way, the reflected lighttravels in the different directions, and is diffused, and thus it ispossible to prevent the reflected light from being concentrated in anarrow range. Hence, it is possible to take light into a wide range onthe indoor side.

As is obvious from what has been described, in the daylighting sheet, itis possible to eliminate at least part of direct light (so-called directsunlight) without significantly reducing the amount of sunlight enteringthe room. In this way, it is possible to form a brighter and morecomfortable indoor space. In this case, in the present embodiment, sincethe light taken into the indoor side is diffused in a wide range of theindoor side, it is possible to efficiently brighten the indoor side.

Furthermore, in the daylighting sheet of the present embodiment, asdescribed above, the light transmission portion 68 is provided, and thefront and back surface of the light deflection layer 67 on the partsarranged in the light transmission portions 68 are formed parallel andsmoothly. Thus, as in the other embodiments described above, it ispossible to visually recognize scenery on the outdoor side from theindoor side.

FIG. 17 is a diagram illustrating a sixth embodiment, is a diagram of anenlarged part of a cross section of a light deflection layer 77 includedin the sixth embodiment and corresponds to FIG. 12. Since the presentembodiment is characterized in the cross-sectional shape of the lightdeflection layer 77, only the light deflection layer 77 will bedescribed. The other parts are the same as described above.

The light deflection layer 77 includes a light transmission portion 78and a light deflection portion 79. The light transmission portion 78 hasa cross section shown in FIG. 17, and is arranged so as to extend in onedirection (the horizontal direction in the position arranged in thebuilding 1) along the surface of the base material layer, and aplurality of light transmission portions 78 are aligned in apredetermined distance in a direction different from the one directionalong the surface of the base material layer (the vertical direction inthe position arranged in the building 1). In the present embodiment,adjacent light transmission portions 78 are integrally coupled at theend portions on the side of the base material layer.

On the other hand, the light deflection portion 79 is arranged betweenthe adjacent light transmission portions 78.

The light transmission portion 78 is a part that transmits light, andthe surface of a part of the light deflection layer 77 where the lighttransmission portion 78 is arranged on the side of the base materiallayer 16 (see FIG. 11) and the surface (the surface on the side of theadhesive layer 12, see FIG. 11) on the opposite side are preferablyformed parallel to each other and smoothly. In this way, it is possibleto more easily see scenery on the outdoor side as in the embodimentsdescribed above.

In the present embodiment, in the cross section shown in FIG. 17, thelight transmission portion 78 has a substantially trapezoidal crosssection between adjacent light deflection portions 79 with a short upperbase on the outdoor side and a long lower base on the indoor side, and aside that forms an interface with the light deflection portion 77 is aleg portion. However, since the leg portion is shaped along the shape ofthe light deflection portion 79, which will be described later, the legportion is not necessarily straight.

The light deflection portion 79 is a part that is formed between twoadjacent light transmission portions 78. Specifically, as describedabove, the light transmission portions 78 are aligned in a predetermineddistance in the direction along the sheet surface of the lighttransmission portion 78, and a groove-shaped concave portion having apredetermined shape is formed between the light transmission portions78. The concave portion in the present embodiment is a groove that has across-sectional shape corresponding to the cross-sectional shape of thelight deflection portion 79, and is filled with the material of thelight deflection portion 79 to form the light deflection portion 79.Hence, the light deflection portion 79 has the cross-sectional shapebased on the concave portion.

The light deflection portion 79 is a part that can totally reflect anddeflect light applied here. Hence, the light deflection portion 79 isfilled with the material whose refractive index is lower than that ofthe light transmission portion 78. Thus, when the light that has enteredthe light deflection portion 79 satisfies total reflection conditions bythe refractive index difference between the light deflection portion 79and the light transmission portion 78 and a relationship of the angle ofthe light entering the interface, it is possible to totally reflect anddeflect the light here. As will be described in detail later, thedeflected light is changed in direction, and for example, the light isapplied to the celling, and thus it is possible to prevent the lightfrom being directly applied without glare being given. In terms ofgeneral versatility of a raw material, the refractive index of thematerial of the light deflection portion 79 is preferably equal to ormore than 1.49 but equal to or less than 1.56, and is more preferablyequal to or more than 1.49 but equal to or less than 1.50.

Here, the refractive index difference between the light transmissionportion 78 and the light deflection portion 79 is equal to or more than0.03 but equal to or less than 0.07, and is more preferably equal to ormore than 0.05 but equal to or less than 0.06. When the refractive indexdifference is more than 0 but less than 0.03, if wavelength dispersion(dispersion caused by the difference of total reflection angles due tothe wavelengths) at the time of total reflection occurs, the componentof a long wavelength may not be totally reflected and only the componentof a short wavelength may be totally reflected, with the result that thecolor is likely to be changed. On the other hand, when the refractiveindex difference is more than 0.07, the refractive index of thecomponent of the short wavelength tends to be higher than the refractiveindex of the component of the long wavelength, with the result thatunevenness in the shape of a rainbow is likely to occur remarkably.

Furthermore, in the present embodiment, the light deflection portion 79has a shape as described below. A description will be given withreference to FIG. 17.

The light deflection portion 79 has a trapezoid in a cross section shownin FIG. 17. In the trapezoid, a long lower base is on the outdoor side(the side of the upper base of the light transmission portion 78), ashort upper base is on the indoor side (the side of the lower base ofthe light transmission portion 78) and leg portions are on the upperside and the lower side.

In the side 79 a on the upper side of the leg portions, in the positionshown in FIG. 17, its inclination angle is inclined at an angle θ_(U4)with respect to the horizontal surface (the normal to the sheet surfaceof the daylighting sheet) toward the upper side of the outdoor side (theside of the sun).

On the other hand, in the side 79 b on the side of the leg portion onthe lower portion side, that is, on the opposite side to the side 79 a,its inclination angle is inclined at a predetermined angle with respectto the horizontal surface (the normal to the sheet surface of thedaylighting sheet) toward the lower side of the outdoor side. Theinclination angle of the side 79 b is not particularly limited but ispreferably equal to or more than 0 degrees but equal to or less than 30degrees in terms of the manufacturing.

Furthermore, the side 79 b is configured to scatter and reflect thelight totally reflected in the side 79 b. Thus, as will be describedlater, it is possible to prevent a problem in which, when thedaylighting sheet is looked up at from the outdoor side, it is possibleto know the state on the indoor side.

Although the specific form for scattering and reflecting the light isnot particularly limited, for example, the side 79 b may be configuredto have minute projections and recesses.

As shown in FIG. 17, the surface of the projections and recesses asdescribed above is preferably stepwise along the inclination of the side79 b. Specifically, its shape is as follows. The size in the directionof thickness of the projections and recesses (the size indicated by T inFIG. 17) is preferably equal to or more than 1 μm but equal to or lessthan 50 μm. When the size is less than 1 μm, it is about the size of thewavelength of light, and thus it is likely that it is impossible toobtain the effect of total reflection in geometric optics. On the otherhand, since the size in the direction of thickness of the lightdeflection layer 77 is preferably equal to or more than 50 μm but equalto or less than 300 μm, when T is more than 50 μm, the surface may notbe stepwise.

The size in the direction of width of the projections and recesses (thesize indicated by S in FIG. 17) is equal to or more than 0.5 μm, andmore preferably is equal to or more than 1.0 μm. On the other hand, thesize in the direction of width is preferably equal to or less than 10μm. When the size is more than 10 μm, the size is excessively close tothe width of the light deflection portion 79, and thus the surface maynot be appropriately stepwise.

A daylighting unit is formed with the daylighting panel having thedaylighting sheet including the light deflection layer 77 describedabove, and is arranged in the opening portion of the building 1 as shownin FIG. 1. Effects and the like in a case where the daylighting sheet isarranged as described above will now be described based on main opticalpaths.

As is obvious from FIG. 17, light L_(S6) is light that is applied to thedaylighting panel at an elevation angle (an angle formed from thehorizontal surface) based on the altitude of the sun at that time. Whilethe light L_(S6) entering the daylighting panel passes through thedaylighting panel, the light L_(S6) travels through the lighttransmission portion 78 of the light deflection layer 77. When thesunlight travelling through the light transmission portion 78 reachesthe interface between the light transmission portion 78 and the lightdeflection portion 79, if the refractive index difference between thelight transmission portion 78 and the light deflection portion 79 and arelationship of the sunlight travel angle are equal to or more than thecritical angle of total reflection, total reflection occurs in theinterface as shown in FIG. 17. In this way, the sunlight is deflected,and thus it is possible to inhibit direct light that causes glare.

On the other hand, for example, when the indoor side is brighter thanthe outdoor side at night, light as indicated by L_(N1) in FIG. 17 isemitted out from the indoor side to the outdoor side. The light includesinformation indicating the state in the indoor side, and may be totallyreflected off the interface between the light transmission portion andthe light deflection portion and be emitted with the information clearlyseen. However, in the present embodiment, since the side 79 b of thelower portion of the light deflection portion 79 has a means forscattering light, as indicated by the light L_(N2) in FIG. 17, the lightincluding the information indicting the state in the indoor side isscattered and is emitted to the outdoor side. Hence, in the daylightingsheet including the light deflection layer 77, since in the lightreflected off the interface between the light transmission portion andthe light deflection portion, the clearness of the light is eliminatedand emitted from the indoor side to the outdoor side, the conditionwhere the state in the indoor side can be seen from the outdoor side isremoved.

FIG. 18 is a diagram illustrating a seventh embodiment, is a diagram ofan enlarged part of a cross section of a light deflection layer 87included in the seventh embodiment and corresponds to FIG. 12. Since thepresent embodiment is characterized in the cross-sectional shape of thelight deflection layer 87, only the light deflection layer 87 will bedescribed. The other parts are the same as described above.

The present embodiment is the same as in the other embodiments in thatthe light deflection layer 87 includes a light transmission portion 88and a light deflection portion 89. However, the present inventiondiffers in that a light absorption portion 89 e which is a part forabsorbing light is provided in the outdoor side of the light deflectionportion 89.

The light absorption portion 89 e is the part that is configured to beable to absorb light applied here. The light absorption portion 89 e isthe part that can absorb 10% or more of visible rays (light of awavelength equal to or more than 360 nm but equal to or less than 830nm). When the absorption rate of visible rays in the light absorptionportion 89 e is not equal to or more than 10%, it is difficult for thelight absorption portion 89 e to achieve a function described later. Theabsorption rate of visible rays in the light absorption portion 89 e ispreferably 90% or less. When the absorption rate of visible rays in thelight absorption portion 89 e is 90% or less, the composition of thelight absorption portion 89 e is easily adjusted.

The thickness of the light absorption portion 89 e (the size in theleft/right direction of FIG. 18) is preferably equal to or more than 1μm but equal to or less than 10 μM. The thickness of the lightabsorption portion 89 e is set at about the thickness described above,and thus the absorption rate of visible rays in the light absorptionportion 89 e is easily made uniform.

The light absorption portion 89 e can be formed with, for example, acomposition in which particles (light absorption particles) having alight absorption property in a translucent resin are scattered.

Here, as the translucent resin, the same resin as that of the lighttransmission portion 88 can be used.

On the other hand, as the light absorption particles, light absorptioncolored particles such as carbon black are preferably used. However, thelight absorption particles are not limited to them, for example, coloredparticles that selectively absorb a predetermined wavelength accordingto the characteristics of light that needs to be absorbed may be used asthe light absorption particles. Specific examples of the coloredparticles include: metal salts such as carbon black, graphite and blackiron oxide; organic fine particles that are colored by dyes, pigments,or the like; and colored glass beads. Among them, in terms of cost,quality, availability and the like, the colored organic fine particlesare preferably used. More specifically, acrylic cross-linked fineparticles containing carbon black, urethane cross-linked fine particlescontaining carbon black and the like are preferably used.

Although in the present embodiment, the light absorption portion 89 e isconfigured as described above, as long as the light absorption portioncan absorb light, its form is not limited. For example, the lightabsorption portion may be formed with a resin colored by a pigment or adye.

With the light deflection layer 87 described above, as described above,it is possible to deflect outside light and take it into the room and toclearly see the outdoor side from the indoor side. Moreover, since thelight absorption portion 89 e is formed in the light deflection layer87, part of the outside light entering the daylighting sheetsubstantially perpendicularly with respect to the sheet surface of thedaylighting sheet enters the light absorption portion 89 e and isabsorbed by it. As described above, the light absorption portion 89 eabsorbs the part of the outside light, and thus it is possible toprevent the indoor side from unnaturally appearing to be white when theindoor side is seen from the outdoor side, and to thereby see the indoorside in natural darkness. If the light absorption portion 89 e is notprovided, the light that has reached the light deflection layer entersthe light deflection portion and is scattered. If the light is scatteredas described above, it is likely that the indoor side unnaturallyappears to be white when the indoor side is seen from the outdoor side.As described above, the light absorption portion 89 e absorbs the partof the outside light, and thus it is possible to prevent the part of thelight reaching the light deflection portion 89 from being scattered bybeing absorbed by the light absorption portion 89 e and to prevent theindoor side from unnaturally appearing to be white when the indoor sideis seen from the outdoor side.

FIG. 19 is a diagram illustrating an eighth embodiment, and is aperspective view of a roll-up daylighting screen 90 to which thedaylighting sheet 15 is applied. As described above, the upper end ofthe daylighting sheet 15 is attached to a shaft member 91, and thedaylighting sheet 15 is configured such that the daylighting sheet 15can be wound and unwound around the shaft, with the result that theroll-up daylighting screen 90 is formed.

The roll-up daylighting screen 90 described above is installed in, forexample, the front surface of the window of a building on the indoorside, and controls light entering the room through the window. FIG. 20shows a diagram illustrating the configuration of layers of thedaylighting sheet 15 in a cross section taken along line XX-XX of FIG.19. As is obvious from FIG. 20, the daylighting sheet 15 is applied tothe roll-up daylighting screen 90, and is wound an unwound to form theroll-up daylighting screen 90.

Here, the thickness of the base material layer 16 is not particularlylimited but is preferably equal to or more than 25 μm but equal to orless than 300 μn. When the base material layer 16 is thinner than thisconfiguration, a crease is more likely to occur. On the other hand, whenthe base material layer 16 is thicker than this configuration, it islikely that it is difficult to wind the daylighting sheet 15.

The elastic modulus of the light transmission portion 18 is preferablyequal to or less than 2000 MPa. This is because, in a case where thedaylighting sheet 15 is applied to the roll-up daylighting screen 90, acrack is prevented from being produced when the daylighting sheet 15 iswound or unwound.

Preferably, on the surface of the outermost layer of the roll-updaylighting screen, a layer that prevents adhering (an adheringprevention layer, a blocking layer) is formed or processing forpreventing adhering is performed. Thus, it is possible to smoothlyunwind the screen by preventing adhering when the screen is unwound(wound back).

In the roll-up daylighting screen 90 described above, the same effect asthe daylighting panel 10 described above is achieved, and, since windingand unwinding can be performed, it is easy to move and use it.

Although here, the example where the daylighting sheet 15 is used as theroll-up daylighting screen has been described, the present invention isnot limited to this configuration, and the roll-up daylighting screenmay be formed by using the daylighting sheet in each form describedabove.

FIG. 21 is a diagram that illustrates a ninth embodiment and thatcorresponds to FIG. 3, and is a diagram showing the configuration oflayers of a daylighting panel 100 in a window to which the daylightingpanel 100 is applied. In the present embodiment, as with the window 1, aframe member is attached to the daylighting panel 100 and its perimeterportion, and thus the window is formed. FIG. 22 shows a part of FIG. 21,that is, an enlarged diagram a light transmission portion 108 of a lightdeflection layer 107 of interest.

Here, the same parts as in the configuration described above areidentified with the same symbols, and their description will not berepeated.

The daylighting panel 100 includes the panel 11, the adhesive layer 12and a daylighting sheet 105 that is adhered to the panel 11 with anadhesive layer 12. The daylighting sheet 105 includes the base materiallayer 16, a light deflection layer 107, the adhesive layer 20, theprotective layer 21 and the hard coat layer 22. FIGS. 21 and 22 areshown in a position where the daylighting panel 100 is attachedperpendicularly to the building or the like, and the left of the planeof FIGS. 21 and 22 is the outdoor side, the right of the plane is theindoor side, the upper portion of the plane is the top and the lowerportion of the plane is the bottom.

The light deflection layer 107 is a layer that has the function ofdeflecting outside light that is light such as sunlight from the outdoorside and transmitting it to the indoor side. As shown in FIGS. 21 and22, in the light deflection layer 107, a plurality of light transmissionportions 108 are aligned. An air gap is formed between adjacent lighttransmission portions 108 to form a light deflection portion 109.

Each light transmission portion 108 is provided on the side of thesurfaces of the base material layer 16 opposite to the adhesive layer12, and is formed to protrude from the base material layer 16 so as tobe convex. In the present embodiment, the light transmission portion 108has a trapezoid in the cross section shown in FIGS. 21 and 22, and isformed to extend in the back/front direction of the plane of the figure(in the present embodiment, the horizontal direction) with the crosssection maintained, and the light transmission portions 108 are alignedin a direction different from the direction of the extension.

In the trapezoidal cross section, the light transmission portion 108includes a first surface 108 a that forms a lower base, a second surface108 b that forms an upper base and a deflection surface 108 c that formsa leg in the lower portion and a rising surface 108 d that forms a legin the upper portion among the surfaces that connect the first surface108 a and the second surface 108 b. Here, the deflection surface 108 cand the rising surface 108 d form the interface with the lightdeflection portion 109.

In the present embodiment, the first surface 108 a faces the outdoorside, and the second surface 108 b faces the indoor side. The firstsurface 108 a and the second surface 108 b are formed substantiallyparallel to each other. The first surface 108 a and the second surface108 b are preferably parallel to the surface of the panel 11.

The deflection surface 108 c is a surface that totally reflects outsidelight in the interface with the light deflection portion 109 based onits refractive index difference and transmits it to the indoor side, andan angle formed with the normal to the surface of the panel 11 is θ₁₁.Although the size of the angle θ₁₁ is not particularly limited as longas outside light is totally reflected and deflected as desired, withconsideration given to the fact that outside light is sunlight andenters in a direction from obliquely above to down, the angle θ₁₁ ispreferably equal to or more than 0 degrees but equal to or less than12.1 degrees, and more preferably is 4.5 degrees. When the angle θ₁₁ is0 degrees, the deflection surface 108 c is parallel to theindoor/outdoor direction. Here, with respect to the positive andnegative signs of the angle θ₁₁, in the position in which thedaylighting panel is vertically installed as in FIG. 22, it is assumedthat the downward inclination from the outdoor side to the indoor sideis negative and that the upward inclination from the outdoor side to theindoor side is positive.

The range of the angle θ₁₁ can be determined with reference to, forexample, three places where latitudes from the south to the north aresignificantly different, that is, Tokyo (35.5 degrees north latitude),Sapporo (43 degrees north latitude) and Naha (26 degrees northlatitude), with consideration given to the refractive index of a generalmaterial which can be used for the culmination altitude of the sun andthe light deflection layer in the summer solstice and the wintersolstice. More specifically, the range of the angle θ₁₁ is as follows.

Tokyo is located at 35.5 degrees north latitude, Sapporo is located at43 degrees north latitude and Naha is located at 26 degrees northlatitude, and the culmination altitudes of the individual areas in thesummer solstice are 78 degrees (Tokyo), 70.5 degrees (Sapporo) and 87.5degrees (Naha). On the other hand, the culmination altitudes in thewinter solstice are 31 degrees (Tokyo), 23.5 degrees (Sapporo) and 40.5degrees (Naha). Hence, the center between the minimum of 23.5 degreesand the maximum of 87.5 degrees in the range is 55 degrees. Here, whenthe refractive index of a general resin is assumed to be 1.49 (acrylicresin) to 1.59 (styrene, polycarbonate resin), total reflectionconditions are calculated based on Snell's law and consideration isgiven to productivity, the angle θ₁₁ is preferably equal to or more than0 degrees but equal to or less than 12.1 degrees, and more preferably is4.5 degrees. When the angle θ₁₁ is less than 0 degrees, machinabilitywhen a mold is manufactured, moldability when the light transmissionportion is molded with the mold and mold release are poor. When theangle θ₁₁ is more than 12.1 degrees, total reflection does not occurwhen the culmination altitude in the summer solstice in Naha is 87.5degrees.

What has been described above is the results obtained by performing thecalculation based on the examples of the area where the daylightingpanel is used. As described above, with consideration given to the anglewhere the culmination altitude is the highest and the angle where theculmination altitude is the lowest in the area where the daylightingpanel is used, it is possible to set an appropriate angle in the area.

The rising surface 108 d is produced by forming the deflection surface108 c. However, the rising surface 108 d is preferably formed to beinclined such that outside light totally reflected off the deflectionsurface 108 c is prevented from being reflected off the rising surface108 d. Specifically, the angle formed by the rising surface 108 dtogether with the normal to the surface of the panel 11 is assumed to bean angle θ₁₂. The size of the angle θ₁₂ is preferably equal to or morethan −75.5 degrees but equal to or less than −26.9 degrees, and morepreferably is −53.3 degrees. The range described above is assumed to bea preferable range of angles at which total reflection does not occurbased on the conditions described above.

The pitch of the light transmission portion 108 is preferably equal toor more than 10 μm but equal to or less than 200 μm. When the pitch isless than 10 μm it is difficult to perform the manufacturing. On theother hand, when the pitch is more than 200 μm, machinability when themold is manufactured, moldability when the light transmission portion108 is molded with the mold and mold release are poor, with the resultthat a problem in the manufacturing may occur. The width of the lighttransmission portion 108 (the width of the lower base of the firstsurface 108 a) is preferably equal to or more than 5 μm but equal to orless than 150 μm. When the width is less than 5 μm, it is difficult toperform the manufacturing. On the other hand, when the width is morethan 150 μm, machinability when the mold is manufactured, moldabilitywhen the light transmission portion is molded with the mold and moldrelease are poor, with the result that a problem in the manufacturingmay occur.

The thickness of the light deflection layer 107 is preferably equal toor more than 50 μm but equal to or less than 300 μm. When the thicknessis less than 50 μm, the optical performance is insufficient or theprocessing of the light deflection layer is fine such that the accuracyis decreased. On the other hand, when the thickness is more than 300 μm,a problem may occur in mold release when the light deflection layer ismolded.

Here, the light transmission portion 108 may be the same material as thebase material layer 16 or may be a different material. However, since arefractive index difference between them increases the possibility thatlight is deflected in the interface, preferably, they are the samematerial or the refractive index difference is low or zero if they aredifferent materials.

When the light transmission portion 108 and the base material layer 16are the same material, the base material layer 16 and the lighttransmission portion 108 can also be formed integrally. When the lighttransmission portion 108 and the base material layer 16 are differentmaterials or even when they are the same material, the base materiallayer 16 and the light deflection layer 107 may be formed separately andbe stacked with any means.

An example of a method of forming the light deflection layer 107 will bedescribed later.

The material that forms the light transmission portion 108 of the lightdeflection layer 107 is not particularly limited but specific examplesof thereof include a transparent resin that has, as main ingredients,one or more of acrylic, styrene, polycarbonate, polyethyleneterephthalate, acrylonitrile and the like and epoxy acrylate andurethane acrylate reactive resins (ionizing radiation curable resin andthe like).

In the present embodiment, the area between adjacent light transmissionportions 108 is filled with air. The refractive index of air is 1.0, andit is possible to obtain a sufficiently high refractive index differencedue to a relationship with the refractive index of the lighttransmission portion 108. Preferably, as the refractive index differenceis increased, the amount of outside light that can be totally reflectedoff the deflection surface 108 c is increased.

However, the present invention is not limited to this configuration, andthe area between adjacent light transmission portions 108 may be filledwith a material having a refractive index lower than that of thematerial of the light transmission portion 108. Specifically, thematerial filling the area is not particularly limited but the examplesthereof include a transparent resin that has, as main ingredients, oneor more of acrylic, styrene, polycarbonate, polyethylene terephthalate,acrylonitrile and the like and epoxy acrylate and urethane acrylatereactive resins (ionizing radiation curable resin and the like).

The deflection surface 108 c and the rising surface 108 d may be aso-called mat surface where minute projections and recesses are formed.In this way, it is possible to take light into the indoor side as thelight is diffused.

The daylighting panel 100 described above can be manufactured asfollows, for example. The light deflection layer 107 can be formed by amethod using a mold roll. Specifically, the mold roll is prepared inwhich on the outer circumferential surface of a cylindrical roll,projections and recesses that can transfer the light transmissionportion 108 of the light deflection layer 107 are prepared. Then,between the mold roll and a nip roll arranged opposite the mold roll,the base material that is the base material layer 16 is inserted. Here,preferably, on one surface of the base material, the adhesive layer 12is previously formed. Then, while the composition of the lighttransmission portion 108 is being supplied between the surface of thebase material on the side where the adhesive layer 12 is not arrangedand the mold roll, the mold roll and the nip roll are rotated. Thus, therecess portions of the projections and recesses formed on the surface ofthe mold roll are filled with the composition of the light transmissionportion 108, and thus the composition is formed along the shape of thesurface of the projections and recesses of the mold roll.

Here, as the composition of the light transmission portion 108, the sameone as the light transmission portion 108 described above can bepreferably applied.

Light is applied from the base material side by a light applicationdevice to the composition of the light transmission portion 108 that issandwiched between the mold roll and the base material and that fillsthat portion. Thus, it is possible to cure the composition of the lighttransmission portion 108 and fix its shape. With a mold release roll,the base material layer 16 and the molded light deflection layer 107 arereleased from the mold roll.

On the other hand, a stack member in which the hard coat layer 22 isstacked on one surface of the protective layer 21 and the adhesive layer20 is stacked on the other surface is prepared, and they are stackedsuch that the adhesive layer 20 is on the side of the second surface 108b of the light transmission portion 108.

When the adhesive layer 20 is formed of an ultraviolet curable resin, aphoto-curable resin or the like, ultraviolet rays or light is preferablyapplied after the stacking.

The stack member formed as described above is adhered to the panel 11with the adhesive layer 12, and thus it is possible to form thedaylighting panel 100.

In the daylighting sheet 100, each of the layers described above mayhave a configuration for adding another function. Examples of thisfunction include a near-infrared absorption function, an ultravioletabsorption function and a heat-ray absorption function. These are asdescribed above.

Then, main optical paths in a case where the windows are formed with thedaylighting panels 100 and they are arranged in the opening portions ofthe building will be described. Schematic examples of the optical pathare shown in FIG. 22.

Outside light L211 applied to the daylighting panel 100 in a directionfrom obliquely above to down from which sunlight is assumed to beapplied passes through the panel 11, the adhesive layer 12 and the basematerial layer 16 and enters the light deflection portion 108 of thelight deflection layer 107. The outside light L211 that has entered thelight deflection portion 108 reaches the deflection surface 108 c, andis totally reflected of the interface and deflected into light thattravels obliquely upwardly. Then, although the outside light L211reaches the rising surface 108 d, since as described above, the risingsurface 108 d has the angle θ₁₂, the outside light L211 passes throughthe rising surface 108 d without being totally reflected in the risingsurface 108 d, passes through the adhesive layer 20, the protectivelayer 21 and the hard coat layer 22 and enters the indoor side. Here,since the outside light L211 is deflected obliquely upwardly, the lightis applied to the ceiling and the back of the space in the indoor sideand functions as light that does not give glare.

Depending on the angle of θ₁₁, it is possible to deflect the lighttoward the horizontal direction or downwardly with respect to thehorizontal direction. Even in this case, it is possible to deflect thelight upwardly with respect to at least the angle of the entrance lightand take the light into the indoor side.

As described above, with the daylighting panel 100, it is possible todeflect the light entering in a direction from obliquely above to down,upwardly with respect to the angle at which the light has entered, andto take the light into the room. Thus, for example, when it isundesirable to apply direct sunlight to a floor surface or a lowerportion of the space, it is possible to take the light into an upperportion of the space without reducing the amount of light.

On the other hand, when the outdoor side is seen from the indoor side,an observer's line of sight corresponds to light L212. In other words,it is possible to observe the outdoor side through the second surface108 b and the first surface 108 a of the light transmission portion 108that are surfaces parallel to the panel 11. Since in this part, a highdegree of refraction is not performed in the interface, it is possibleto clearly see scenery on the outdoor side.

As described above, with the daylighting panel 100, it is possible toappropriately deflect outside light and relatively clearly see outsidescenery from the indoor side. Moreover, although the light deflectionlayer 107 has the projections and recesses, since it is sandwichedbetween the base material layer 16 and the protective layer 21, it ispossible to enhance the durability.

On the other hand, since each light transmission portion 108 of thelight deflection layer 107 is strongly held by the first surface 108 aand the second surface 108 b of the light transmission portion 108 withthe base material layer 16 and the protective layer 21, the stability ofproduction is excellent, the handing of the product is easy and thestability of the shape is excellent.

FIG. 23 is a diagram illustrating a tenth embodiment, and corresponds toFIG. 22 of a daylighting panel 110. The daylighting panel 110 differsfrom the daylighting panel 100 in that, instead of the daylighting sheet105 of the daylighting panel 100 described above, a daylighting sheet115 is applied. More specifically, the daylighting sheet 115 differsfrom the daylighting sheet 105 in that, instead of the light deflectionlayer 107, a light deflection layer 117 is applied. The description ofthe daylighting sheet 100 applies to the other constituent members, andthus their description will not be repeated.

As shown in FIG. 23, in the light deflection layer 117, a plurality oflight transmission portions 118 are aligned. An air gap is formedbetween adjacent light transmission portions 118 to form a lightdeflection portion 119. The light transmission portion 118 is providedon the side of the surfaces of the base material layer 16 opposite tothe adhesive layer 12, and is formed to protrude from the base materiallayer 16 so as to be convex. In the present embodiment, the lighttransmission portion 118 has a trapezoid in the cross section in thedirection of the thickness in the vertical direction, and is formed toextend in the back/front direction of the plane of the figure (that is,the horizontal direction) with the cross section maintained, and thelight transmission portions 118 are aligned in a direction differentfrom the direction of the extension.

In the trapezoidal cross section, the light transmission portion 118includes a first surface 118 a that forms a lower base, a second surface118 b that forms an upper base and a deflection surface 118 c that formsa leg in the lower portion and a rising surface 118 d that forms a legin the upper portion among the surfaces that connect the first surface118 a and the second surface 118 b. Here, the deflection surface 118 cand the rising surface 118 d form the interface with the lightdeflection portion 119.

In the present embodiment, the first surface 118 a faces the outdoorside, and the second surface 118 b faces the indoor side. The firstsurface 118 a and the second surface 118 b are formed substantiallyparallel to each other. The first surface 118 a and the second surface118 b are preferably parallel to the surface of the panel 11.

In the present embodiment, the deflection surface 118 c is a surfacethat refracts outside light and transmits it to the indoor side, and anangle formed with the normal to the surface of the panel 11 is θ₁₃.Although the size of the angle θ₁₃ is not particularly limited as longas outside light is refracted and deflected as desired, withconsideration given to the fact that outside light is sunlight andenters in a direction from obliquely above to down, the angle θ₁₃ ispreferably equal to or more than 5.7 degrees but equal to or less than51.1 degrees, and more preferably is 29.3 degrees. This is also based onthe idea of the description of the angle θ₁₁, and the range in whichappropriate refraction is possible is determined. When the angle θ₁₃ isless than 5.7 degrees, it is impossible to refract the outside lightwhereas when the angle is more than 51.1 degrees, the outside light maybe refracted downwardly.

However, as with the angle θ₁₁, the angle θ₁₃ is preferably adjustedbased on the culmination altitude of the area where the daylightingpanel 110 is used.

The rising surface 118 d is produced by forming the deflection surface118 c. In the present embodiment, since the outside light refracted bythe deflection surface 118 c little reaches the rising surface 118 d,the angle θ₁₄ formed by the rising surface 118 d together with thenormal to the surface of the panel 11 is not particularly limited.However, since machinability when the mold is manufactured, moldabilitywhen the light transmission portion is molded with the mold and moldrelease are poor, and thus a problem in the manufacturing may occur, theangle θ₁₄ is equal to or less than 0 degrees, and preferably is 0degrees.

The pitch and the like of the light transmission portion 118 are thesame as those of light transmission portion 108. The material of thelight transmission portion 118 and the form between the adjacent lighttransmission portions 118 (that is, the light deflection portion 119)are the same as those of the light deflection layer 107 described above.

The deflection surface 118 c and the rising surface 118 d may be aso-called mat surface where minute projections and recesses are formed.In this way, it is possible to take light into the indoor side as thelight is diffused.

Then, main optical paths in a case where the windows are formed with thedaylighting panels 110 and they are arranged in the opening portions ofthe building will be described. Schematic examples of the optical pathare shown in FIG. 23.

Outside light L231 applied to the daylighting panel 110 in a directionfrom obliquely above to down from which sunlight is assumed to beapplied passes through the panel 11, the adhesive layer 12 and the basematerial layer 16 and reaches the light transmission portion 118 of thelight deflection layer 117. The outside light L231 that has entered thelight transmission portion 118 reaches the deflection surface 118 c, isrefracted in the interface and is deflected into light which travelsmore upwardly than before the refraction. Then, the light passes throughthe adhesive layer 20, the protective layer 21 and the hard coat layer22, and enters the indoor side. Here, since the outside light L231 isdeflected upwardly as compared with the entrance light, the light isapplied to the back of the space in the indoor side.

As described above, with the daylighting panel 110, it is possible todeflect the light entering in a direction from obliquely above to down,upwardly with respect to the angle at which the light has entered, andto take the light into the room. Thus, for example, when it isundesirable to apply direct sunlight to a floor surface or a lowerportion of the space, it is possible to take the light into the back ofthe space without reducing the amount of light.

On the other hand, when the outdoor side is seen from the indoor side,an observer's line of sight corresponds to light L232. In other words,it is possible to observe the outdoor side through the second surface118 b and the first surface 118 a of the light transmission portion 118that are surfaces parallel to the panel 11. Since in this part, a highdegree of refraction is not performed in the interface, it is possibleto clearly see scenery on the outdoor side.

As described above, with the daylighting panel 110, it is possible toappropriately deflect outside light and relatively clearly see outsidescenery from the indoor side. Moreover, since the light deflection layer117 having the projections and recesses is sandwiched between the basematerial layer 16 and the protective layer 21, it is possible to enhancethe durability.

On the other hand, since each light transmission portion 118 of thelight deflection layer 117 is strongly held by the first surface 118 aand the second surface 118 b of the light transmission portion 118 withthe base material layer 16 and the protective layer 21, the stability ofproduction is excellent, the handing of the product is easy and thestability of the shape is excellent.

FIG. 24 is a diagram illustrating an eleventh embodiment, andcorresponds to FIG. 22 of a daylighting panel 150. The daylighting panel150 differs from the daylighting panel 100 in that, instead of thedaylighting sheet 105 of the daylighting panel 100 described above, adaylighting sheet 155 is applied. More specifically, the daylightingsheet 155 differs from the daylighting sheet 105 in that, instead of thelight deflection layer 107, a light deflection layer 157 is applied. Thedescription of the daylighting sheet 100 applies to the otherconstituent members, and thus their description will not be repeated.

As shown in FIG. 24, in the light deflection layer 157, a plurality oflight transmission portions 158 are aligned. An air gap is formedbetween adjacent light transmission portions 158 to form a lightdeflection portion 159. The light transmission portion 158 is providedon the side of the surfaces of the base material layer 16 opposite tothe adhesive layer 12, and is formed to protrude from the base materiallayer 16 so as to be convex. In the present embodiment, the lighttransmission portion 158 has a shape described below on the crosssection in the direction of the thickness in the vertical direction, andis formed to extend in the back/front direction of the plane of thefigure (that is, the horizontal direction) with the cross sectionmaintained, and the light transmission portions 158 are aligned in adirection different from the direction of the extension.

While the light deflection portion 159 is formed to be an air gap in thepresent embodiment, the formation of the light deflection portion 159 isnot limited to an air gap but the light deflection portion 159 may befilled with a transparent resin of a lower refractive index than thelight transmission portion 158.

FIG. 25 shows one cross section of the light transmission portion 158.As is seen from FIG. 25, the light transmission portion 158 of thepresent embodiment has a bottom side surface 158 a and a top sidesurface 158 b. The top side surface 158 b includes a first top sideemission surface 158 c, a second top side emission surface 158 d and atop side reflection surface 158 e in this order from the observer side.

The bottom side surface 158 a is a surface where upward total reflectionoccurs to light that enters the bottom side surface 158 a with anentrance angle equal to or more than the critical angle. An angle formedby the bottom side surface 158 a together with the normal to the surfaceof the base material layer 16 is preferably 0° to 12°.

The first top side emission surface 158 c and the second top sideemission surface 158 d of the top side surface 158 b are surfaces thattransmit and emit the light to which total reflection occurred on thebottom side surface 158 a as the light directs upwards. The firstemission surface 158 c and the second emission surface 158 d arecontinuously formed from the top side reflection surface 158 e, to be ashape of a polygonal line on the cross section. This shape of apolygonal line is formed so as to be convex upwards by the firstemission surface 158 c and the second emission surface 158 d.

When it is assumed that an angle formed by the line connecting a pointof the top side surface 158 b that touches the base material layer 16,and a point of the top side surface 158 b that touches the adhesivelayer 20 together with the normal to the base material layer 16 is setto be γ, an angle β formed by the first emission surface 158 c togetherwith the normal to the surface of the base material layer 16 ispreferably γ to 40°.

The top side reflection surface 158 e is a surface where reflection tothe side of the bottom side surface 158 a occurs to light whose entranceangle thereto is equal to or more than the critical angle. Light whoseentrance angle thereto is less than the critical angle is refracted bythe interface of the top side reflection surface 158 e and the lightdeflection portion 159, to be emitted upwards.

An angle η formed by the top side reflection surface 158 e together withthe normal to the surface of the base substrate layer 16 is preferablyset to be equal to or more than the above described β. If η is less thanβ, most of the light to which total reflection occurs on the top sidereflection surface 158 e does not reach the bottom side surface 158 a.

The top side reflection surface 158 e is preferably structured so as tobe concave downwards at a linking portion with the second top sideemission surface 158 d.

Distance J of the top side reflection surface 158 e in the thicknessdirection is preferably within the range of the following formula:0.7S≦J≦0.9Swhere S represents P tan(π/2−2α−arcsin(1/n)). P represents a pitch ofthe light transmission portion 158 (mm) and n represents the refractiveindex of the light transmission portion 158.

In a case where the distance J is less than 0.7S, most of light thatenters in a direction from obliquely above to down is light whoseentrance angle to the top side reflection surface 158 e is less than thecritical angle, and thus total reflection to the bottom side surface 158a is impossible to occur to most of entering light. In a case where thedistance J is beyond 0.9S, even if light equal to or more than thecritical angle enters the top side reflection surface 158 e in adirection from obliquely above to down, most of light to which totalreflection occurred on the top side reflection surface 158 e does notenter the bottom side surface 158 a.

Inclusion of such a light deflection layer 157 makes it possible to takelight in the outdoor side into the indoor side as light L241 and lightL242, which are examples of the optical path in FIG. 24.

Outside light L241 applied to the light deflection layer 157 in adirection from obliquely above to down from which sunlight is assumed tobe applied passes through the base material layer 16 and enters thelight transmission portion 158 of the light deflection layer 157. Theoutside light L241 that has entered the light transmission portion 158reaches the bottom side surface 158 a, total reflection occurs theretoon the interface and the outside light L241 is deflected into lightwhich travels upwards. Then, the light passes through the other layers,and enters the indoor side. Here, since the outside light L241 isdeflected upwards as compared with the entrance light, the light isapplied to the top part of the space in the indoor side.

Another outside light L242 applied to the light deflection layer 157 ina direction from obliquely above to down from which sunlight is assumedto be applied passes through the base material layer 16 and enters thelight transmission portion 158 of the light deflection layer 157. Theoutside light L242 that has entered the light transmission portion 158reaches the top side reflection surface 158 e of the top side surface158 b, total reflection occurs thereto on the interface to change itsangle, and the outside light L242 is deflected into light which travelsdownwards. Then, the outside light L242 reaches the bottom side surface158 a, total reflection occurs thereto on the interface and the outsidelight L242 is deflected into light which travels upwards. The lightpasses through the other layers, and enters the indoor side. Here, sincethe outside light L242 is deflected upwards as compared with theentrance light, the light is applied to the top part of the space in theindoor side. This light L242 would not reach the bottom side surface 158a if there were no top side reflection surface 158 e. The top sidereflection surface 158 e makes it possible to change the direction ofthe light as described above, to effectively take the light.

According to the daylighting panel including such a light deflectionlayer, it is also possible to deflect the light entering in a directionfrom obliquely above to down, upwardly with respect to the angle atwhich the light has entered, and to take the light into the room. Thus,for example, when it is undesirable to apply direct sunlight to a floorsurface or a lower portion of the space, it is possible to take thelight into the back of the space without reducing the amount of light.

On the other hand, when the outdoor side is seen from the indoor side,an observer's line of sight corresponds to light L243. In other words,as is the same to the above described embodiments, it is possible toobserve the outdoor side through two parallel surfaces of the lighttransmission portion 158 which are surfaces parallel to the panel. Sincein this part, a high degree of refraction is not performed in theinterface, it is possible to clearly see scenery on the outdoor side.

FIG. 26 is a diagram that illustrates a daylighting panel 120 accordingto a twelfth embodiment and that corresponds to FIG. 21. Hence, FIG. 26is a diagram schematically showing the configuration of layers of thedaylighting panel 120. FIG. 27 shows a part of FIG. 26, that is, anenlarged diagram of a light deflection layer 127 of interest.

The daylighting panel 120 includes the panel 11, the adhesive layer 12and a daylighting sheet 125. The daylighting sheet 125 includes theprotective layer 21, the adhesive layer 20, the light deflection layer127, the base material layer 16 and the hard coat layer 22. Theindividual layers will be described below. The same layers as the layersdescribed above are identified with the same symbols, and theirdescription will not be repeated.

The light deflection layer 127 is a layer that has the function ofdeflecting outside light that is light such as sunlight from the outdoorside and transmitting it to the indoor side. As shown in FIGS. 26 and27, in the light deflection layer 127, a plurality of light transmissionportions 128 are aligned.

The light transmission portion 128 is provided on the side of thesurfaces of the adhesive layer 20 opposite to the protective layer 21.In the present embodiment, the light transmission portion 128 has atrapezoid in the cross section in the direction of the thickness in thevertical direction, and is formed to extend in the back/front directionof the plane of the figure (that is, the horizontal direction) with thecross section maintained, and the light transmission portions 128 arealigned in a direction different from the direction of the extension.

In the trapezoidal cross section, the light transmission portion 128includes a first surface 128 a that forms a lower base, a second surface128 b that forms an upper base and a deflection surface 128 c that formsa leg in the lower portion and a rising surface 128 d that forms a legin the upper portion among the surfaces that connect the first surface128 a and the second surface 128 b. Here, the deflection surface 128 cand the rising surface 128 d form the interface with the lightdeflection portion 129.

In the present embodiment, the first surface 128 a faces the indoorside, and the second surface 128 b faces the outdoor side. The firstsurface 128 a and the second surface 128 b are formed substantiallyparallel to each other. The first surface 128 a and the second surface128 b are preferably parallel to the surface of the panel 11.

In the present embodiment, the deflection surface 128 c is a surfacethat totally reflects outside light and that transmits it to the indoorside, and an angle formed with the normal to the surface of the panel 11is θ₁₅. Although the size of the angle θ₁₅ is not particularly limitedas long as outside light is totally reflected and deflected as desired,with consideration given to the fact that outside light is sunlight andenters in a direction from obliquely above to down, the angle θ₁₅ ispreferably equal to or more than −87.5 degrees but equal to or less than−36.5 degrees, and more preferably is −49.5 degrees. The range describedabove is obtained by the same idea as the angle θ₁₁ from the conditionsunder which the light is totally reflected off the deflection surface128 c.

In other words, as with the angle θ₁₁, the angle θ₁₅ is also preferablyadjusted based on the culmination altitude of the area where thedaylighting panel 120 is used.

The rising surface 128 d is produced by forming the deflection surface128 c. However, the rising surface 128 d is preferably formed to beinclined such that outside light entering the light transmission portion128 is prevented from being reflected off the rising surface 128 d.Specifically, the angle formed by the rising surface 128 d together withthe normal to the surface of the panel 11 is assumed to be an angle θ₁₆.The size of the angle θ₁₆ is preferably equal to or more than 2.5degrees but equal to or less than 66.5 degrees, and more preferably is35 degrees. The range described above is also obtained from theconditions under which the light is not totally reflected off the risingsurface 128 d and enters the light transmission portion 128.

The pitch and the like of the light transmission portion 128 are thesame as those of light transmission portion 118. The second surface 128b of the light transmission portion 128 is adhered to the adhesive layer20. The other configurations such as the material of the lighttransmission portion 128 are the same as those of the light transmissionportion 108 of the daylighting panel 100 described above.

The deflection surface 128 c and the rising surface 128 d may be aso-called mat surface where minute projections and recesses are formed.In this way, it is possible to take light into the indoor side as thelight is diffused.

Then, main optical paths in a case where the windows are formed with thedaylighting panels 120 and they are arranged in the opening portions ofthe building will be described. Schematic examples of the optical pathare shown in FIG. 27.

Outside light L251 applied to the daylighting panel 120 in a directionfrom obliquely above to down from which sunlight is assumed to beapplied passes through the panel 11, the adhesive layer 12, theprotective layer 21 and the adhesive layer 20 and enters the lightdeflection portion 128 of the light deflection layer 127. Although theoutside light L251 reaches the rising surface 128 d when entering thelight transmission portion 128, since as described above, the risingsurface 128 d has the angle θ₁₆, the outside light L251 enters the lighttransmission portion 128 without being totally reflected here. Theoutside light L251 that has entered the light transmission portion 128reaches the deflection surface 128 c, is totally reflected off theinterface and is deflected into light which travels obliquely upwardly.Then, the outside light L251 passes through the base material layer 16and the hard coat layer 22 and enters the indoor side. Here, since theoutside light L251 is deflected obliquely upwardly, the light is appliedto the ceiling and the back of the space in the indoor side.

Depending on the angle of θ₁₅, it is possible to deflect the lighttoward the horizontal direction or downwardly with respect to thehorizontal direction. Even in this case, it is possible to deflect thelight upwardly with respect to at least the angle of the entrance lightand take the light into the indoor side.

As described above, with the daylighting panel 120, it is possible todeflect the light entering in a direction from obliquely above to down,upwardly with respect to the angle at which the light has entered, andto take the light into the room. Thus, for example, when it isundesirable to apply direct sunlight to a floor surface or a lowerportion of the space, it is possible to take the light into an upperportion of the space without reducing the amount of light.

On the other hand, when the outdoor side is seen from the indoor side,an observer's line of sight corresponds to light L252. In other words,it is possible to observe the outdoor side through the second surface128 b and the first surface 128 a of the light transmission portion 128that are surfaces parallel to the panel 11. Since in this part, a highdegree of refraction is not performed in the interface, it is possibleto clearly see scenery on the outdoor side.

FIG. 28 is a diagram illustrating a daylighting panel 130 according to athirteenth embodiment, and corresponds to FIG. 27. The daylighting panel130 differs from the daylighting panel 120 in that, instead of the lightdeflection layer 127 of the daylighting panel 120 described above, alight deflection layer 137 is applied. The description of thedaylighting sheet 120 applies to the other constituent members, and thustheir description will not be repeated.

As shown in FIG. 28, in the light deflection layer 137, a plurality oflight transmission portions 138 are aligned. An air gap is formedbetween adjacent light transmission portions 138 to form a lightdeflection portion 139. The light transmission portion 138 is providedon the side of the surfaces of the base material layer 16 opposite tothe hard coat layer 22, and is formed to protrude from the base materiallayer 16 so as to be convex. In the present embodiment, the lighttransmission portion 138 has a trapezoid in the cross section in thedirection of the thickness in the vertical direction, and is formed toextend in the back/front direction of the plane of the figure (that is,the horizontal direction) with the cross section maintained, and thelight transmission portions 138 are aligned in a direction differentfrom the direction of the extension.

In the trapezoidal cross section, the light transmission portion 138includes a first surface 138 a that forms a lower base, a second surface138 b that forms an upper base and a deflection surface 138 c that formsa leg in the lower portion and a rising surface 138 d that forms a legin the upper portion among the surfaces that connect the first surface138 a and the second surface 138 b. Here, the deflection surface 138 cand the rising surface 138 d form the interface with the lightdeflection portion 139.

In the present embodiment, the first surface 138 a faces the indoorside, and the second surface 138 b faces the outdoor side. The firstsurface 138 a and the second surface 138 b are formed substantiallyparallel to each other. The first surface 138 a and the second surface138 b are preferably parallel to the surface of the panel 11.

In the present embodiment, the deflection surface 138 c is a surfacethat refracts outside light and transmits it to the indoor side, and anangle formed with the normal to the surface of the panel 11 is θ₁₇.Although the size of the angle θ₁₇ is not particularly limited as longas outside light is refracted and deflected as desired, withconsideration given to the fact that outside light is sunlight andenters in a direction obliquely above to down, the angle θ₁₇ ispreferably equal to or more than −87.5 degrees but equal to or less than−23.5 degrees, and more preferably is −55 degrees. This is also based onthe idea of the description of the angle θ₁₁, and the range in whichappropriate refraction is possible in the deflection surface 138 c isdetermined. In other words, it is possible to perform a setting asnecessary based on the culmination altitude of the area where thedaylighting panel 130 is used.

The rising surface 138 d is produced by forming the deflection surface138 c. In the present embodiment, since the outside light refracted bythe deflection surface 138 c little reaches the rising surface 138 d,the angle θ₁₈ formed by the rising surface 138 d together with thenormal to the surface of the panel 11 is not particularly limited.However, since machinability when the mold is manufactured, moldabilitywhen the light transmission portion is molded with the mold and moldrelease are poor, and thus a problem in the manufacturing may occur, theangle θ₁₈ is equal to or less than 0 degrees, and preferably is 0degrees.

The pitch and the like of the light transmission portion 138 are thesame as those of light transmission portion 128. The material of thelight transmission portion 138 and the form between the adjacent lighttransmission portions 138 are the same as those of the light deflectionlayer 127 described above.

Then, main optical paths in a case where the windows are formed with thedaylighting panels 130 and they are arranged in the opening portions ofthe building will be described. Schematic examples of the optical pathare shown in FIG. 28.

Outside light L261 applied to the daylighting panel 130 in a directionfrom obliquely above to down from which sunlight is assumed to beapplied passes through the panel 11, the adhesive layer 12, theprotective layer 21 and the adhesive layer 20 and reaches the lighttransmission portion 138 of the light deflection layer 137. In thiscase, the outside light L261 reaches the deflection surface 138 c, isrefracted in the interface and is deflected into light which travelsmore upwardly than before the refraction. Then, the light passes throughthe base material layer 16 and the hard coat layer 22, and enters theindoor side. Here, since the outside light L261 is deflected upwardly ascompared with the entrance light, the light is applied to the back ofthe space in the indoor side.

As described above, with the daylighting panel 130, it is possible todeflect the light entering in a direction from obliquely above to down,upwardly with respect to the angle at which the light has entered, andto take the light into the room. Thus, for example, when it isundesirable to apply direct sunlight to a floor surface or a lowerportion of the space, it is possible to take the light into the back ofthe space without reducing the amount of light.

On the other hand, when the outdoor side is seen from the indoor side,an observer's line of sight corresponds to light L262. In other words,it is possible to observe the outdoor side through the second surface138 b and the first surface 138 a of the light transmission portion 138that are surfaces parallel to the panel 11. Since in this part, a highdegree of refraction is not performed in the interface, it is possibleto clearly see scenery on the outdoor side.

FIG. 29 is a diagram illustrating the thirteenth embodiment, and is aperspective view of a roll-up daylighting screen 140 to which thedaylighting sheet 105 is applied. As described above, the upper end ofthe daylighting sheet 105 is attached to a shaft member 141, and thedaylighting sheet 105 is configured such that the daylighting sheet 105can be wound and unwound around the shaft, with the result that theroll-up daylighting screen 140 is formed.

The roll-up daylighting screen 140 described above is installed in, forexample, the front surface of the window of a building on the indoorside, and controls light entering the room through the window.

As described above, as with the roll-up daylighting screen 90 describedabove, the roll-up daylighting screen 140 can be configured such thatthe daylighting sheet 105, 115, 125 or 135 can be wound and unwound.

In each of the embodiments described above, the example where the lighttransmission portion and the light deflection portion have thepredetermined cross section to extend in the horizontal direction, and aplurality of light transmission portions and light deflection portionsare aligned in the vertical direction has been described. However, thepresent invention is not limited to this configuration, and, forexample, the light transmission portion and the light deflection portioncan have a predetermined cross section to extend in the verticaldirection, and a plurality of light transmission portions and lightdeflection portions can be aligned in the horizontal direction. In thisway, it is possible to perform daylighting while reducing direct lightfrom the east side and the west side to a south facing window in themorning and the evening.

LIST OF REFERENCE SYMBOLS

-   -   1 window    -   2 frame    -   10, 30, 40, 50 daylighting panel    -   11 panel    -   12 adhesive layer    -   15, 35, 45, 55, 105, 125 daylighting sheet    -   16 base material layer    -   17, 37, 47, 57, 67, 77, 87, 107, 117, 127, 137, 157 light        deflection layer    -   18, 58, 68, 78, 88, 108, 118, 128, 138, 158 light transmission        portion    -   19, 39, 59, 69, 79, 89, 109, 119, 129, 139, 159 light deflection        portion    -   20 adhesive layer    -   21 protective layer    -   22 hard coat layer    -   90, 140 roll-up daylighting screen

What is claimed is:
 1. A daylighting sheet that is arranged in anopening portion of a building and transmits light from an outdoor sideto an indoor side, wherein the daylighting sheet is formed by stacking aplurality of layers, the layers include: a translucent base materiallayer; and a light deflection layer that is formed on the base materiallayer, and the light deflection layer includes: light transmissionportions that are aligned along one surface of the base material layerso as to be able to transmit light, each of the light transmissionportions including a portion that is convex upward and a portion that isconvex downward, the portions being in a top side in a position wherethe light transmission portion is arranged in the opening portion of thebuilding, the portion downward being arranged closer to the basematerial layer than the portion upward is; and light deflection portionsthat are formed between the light transmission portions and filled witha material whose refractive index is lower than that of the lighttransmission portions, and wherein on a cross section in a thicknessdirection, assuming that an angle formed by a line connecting a positionat the top side that is closest to the base material layer and aposition at the top side that is opposite to the position closest to thebase material layer, together with a normal to a layer surface of thebase material layer is γ, and that an angle formed by a side of theportion upward that is farthest from the base material layer togetherwith the normal is β, the angle β is no less than the angle γ and nomore than 40°, assuming that an angle formed by a side of the portiondownward that is closest to the base material layer together with thenormal is η, the angle η is no less than the angle β, assuming thatdistance of the side forming the angle n in the thickness direction isJ, a pitch of the light transmission portion is P, and an angle formedby a bottom side of the light transmission portion in a position wherethe daylighting sheet is arranged in the opening portion of thebuilding, together with the normal is α, the refractive index of thelight transmission portion is n, and the formulaJ=Ptan(π/2−2α−arcsin(1/n)) is satisfied, 0.7S≦J≦0.9S.
 2. The daylightingsheet of claim 1, wherein the light deflection portions are filled withair.
 3. The daylighting sheet of claim 1, wherein the light deflectionportions are filled with a transparent resin.
 4. The daylighting sheetof claim 1, wherein a portion in the bottom side of the lighttransmission portion, the portion being opposite to the portion that isin the top side, is a straight line on the cross section.
 5. Thedaylighting sheet of claim 1, wherein at least one of other translucentlayers is arranged on a side of the light deflection layer opposite tothe base material layer.
 6. The daylighting sheet of claim 1, whereinthe light transmission portions have a predetermined cross section andextend along the one surface of the base material layer, and are alignedin a direction different from the direction in which the lighttransmission portions extend, and the light deflection portions arearranged between the adjacent light transmission portions such that thelight deflection portions extend in the same direction as the lighttransmission portions and are aligned in the direction different fromthe direction in which the light transmission portions extend.
 7. Adaylighting panel comprising: a translucent plate-shaped panel; and thedaylighting sheet of claim 1 that is attached to one surface of thepanel.
 8. The daylighting panel of claim 7, wherein the panel is awindow glass that is provided in the opening portion of the building. 9.A roll-up daylighting screen comprising: the daylighting sheet of claim1; and a shaft member that is arranged in the daylighting sheet suchthat the daylighting sheet can be wound and unwound.